Short wavelength visible light-emitting toothbrush with an electronic signal interlock control

ABSTRACT

A short wavelength visible light-emitting toothbrush with an electronic interlock control device preventing operation when the toothbrush is removed from the user&#39;s mouth. The electronic interlock control over operation is necessary to prevent accidental eye exposure to the high intensity light source with a wavelength in the range of 400 nm to 500 nm. The light-emitting toothbrush activates upon entering the user&#39;s mouth but deactivates immediately when removed, thus protecting the user&#39;s eyes from direct exposure to the high power light source contained in the brush head.

BACKGROUND OF THE INVENTION

The present invention relates to increasing the safety of a dentalhygiene implement such as a light-emitting manual or an electricallyoperated motorized toothbrush which emits radiation, in the violetand/or blue region of the visible spectrum, between 400 nm and 500 nm,in order to:

-   -   oxidize and destroy potentially harmful bacteria and/or other        contaminants or compounds contained within the mouth without        harming or destroying human cells;    -   exert a phototoxic effect on pathogenic periodontal and oral        bacteria such as; P. Gingivalis and F. Nucleatum, and S. Mutans;    -   activate a photo catalyst that may be deposited on the teeth and        the gums of the person utilizing the toothbrush during normal        brushing; and/or    -   accelerate the whitening effects of a tooth bleaching agent        added to toothpaste or toothgel such as carbamide peroxide or        hydrogen peroxide.

The electronic interlock control mechanism in this toothbrush willreduce the possibility of accidental direct eye exposure to high fluxvisible light radiation emitted from this toothbrush when it is removedfrom the mouth.

Light-emitting toothbrushes have been developed over the past severalyears for teeth whitening applications in addition to the known oralhygiene benefits of regular brushing. When combined with a teethwhitening agent such as carbamide peroxide or hydrogen peroxide, studieshave shown that light in the 400-500 nm range accelerates the whiteningeffect of these agents. Wolfgang Buchallaa, Thomas Attina: Externalbleaching therapy with activation by heat, light or laser—A systematicreview; Karen Luk, D. D. S.; Laura Tam, D. D. S., M. Sc.; ManfredHubert, Ph.D.: Effect of light energy on peroxide tooth bleaching.

In addition, violet light in the 400 nm-420 nm range has been shown tohave a phototoxic effect on pathogenic oral bacteria such as P.Gingivalis, S. Mutans and others. Michelle Maclean, Scott J. MacGregor,John G. Anderson, and Gerry Woolsey: Inactivation of Bacterial Pathogensfollowing Exposure to Light from a 405-Nanometer Light-Emitting DiodeArray. Doron Steinberg, Daniel Moreinos, John Featherstone, MosheShemesh, and Osnat Feuerstein: Genetic and Physiological Effects ofNoncoherent Visible Light Combined with Hydrogen Peroxide onStreptococcus mutants in Biofilm. The inventors have previously shownthe use of a light-emitting diode (LED) within a toothbrush providesanti-microbial properties of benefit to the oral hygiene of theend-user.

Current light-emitting toothbrushes have a manual on/off switch whichactivates the light-emitting device. This manual activation mechanismmay lead to a safety risk because the user may activate the light andexpose his or her eyes to high levels of light that may be harmful tothe retina or optic nerve. The potentially harmful properties of visiblelight and maximum exposure levels are documented in ANSI standards.François C. Delori, Robert H. Webb, David H. Sliney: Maximum permissibleexposures for ocular safety (ANSI 2000), with emphasis on ophthalmicdevices. David H. Sliney, M. S.: Biohazards of Ultraviolet, Visible andInfrared Radiation. For example, the maximum permissible radiant power(thermal and photo-acoustic) entering a dilated pupil is 1.5×10⁻⁴ Watts.This limit would be exceeded if a user were to stare at a 420 nm LED of250 mW radiant flux at a distance of 10 cm for a period of 0.5 seconds.To prevent accidental eye exposure, a special electronic interlockcontrol mechanism has been implemented to keep the optical source turnedoff if the toothbrush is not inserted in the user's mouth. The controlmechanism will turn the optical source off immediately if the toothbrushis removed from the mouth prior to completing the brushing cycle.

A toothbrush is typically used in close proximity to the eyes of theuser, and if ocular exposure to the light lasts several seconds, eyedamage may occur. Furthermore, the ocular safety risk of manuallyactivated light precludes the use of more powerful light-emittingdevices such as high-powered LEDs, laser diodes, or vertical cavitysurface emitting lasers, which would increase the teeth-whitening andantimicrobial benefits in proportion to the energy delivered. Forexample, studies show that effective whitening treatments require aminimum energy density of 30-50 J cm⁻² to produce noticeable shadewhitening. However, such energy levels would not be readily achievablewith a typical two minute brushing interval using a low-powered LED thatwould also be safe when directly placed in front of the eyes, even whenused over a period of several weeks. Similar limitations exist for theanti-microbial properties of violet light as well.

It is therefore desirable to control the “on” state of thelight-emitting device to a time period when it is in use in the oralcavity but to shut “off” this high power light source immediately, whenit is removed from the mouth to prevent direct eye exposure. Thisfeature would also extend battery life of a battery operated brush sincepower is only used to illuminate the light source when in direct contactwith the oral cavity.

SUMMARY OF THE INVENTION

This invention relates to increasing the safety of a dental hygieneimplement that emits radiation in the violet and/or blue region of thevisible spectrum, between 400 nm and 500 nm, by determining whether theimplement is within the user's mouth or outside of the user's mouth.Direct eye exposure to such light can be avoided using a sensor orcombination of sensors that deactivate the light source whenever it isoutside the environment of the mouth and permits activation only wheninside the mouth of the user.

In one embodiment, the dental hygiene implement may be a light emittingtoothbrush. The light emitting toothbrush, according to the presentinvention, will typically further include a control circuitry which willtypically be located in the handle and normally include functions suchas a timer circuitry (which times the duration(s) of use of thetoothbrush while brushing), an on/off duty cycle of the violet lightsource or sources, a battery replacement indicator, and so on.

Preferably the driver, for driving the violet light source, is equippedwith constant electrical current control electronics and a suitabledriver is supplied by Linear Technology, of San Jose Calif., as part no.LTC3454 which is an integrated circuit high current LED driver. Thecontrol circuitry may also include violet light source controlcircuitry, which may be connected with one or more sensors located inthe brush head, for detecting when the brush head is actually locatedwithin a user's mouth, thereby reducing the possibility of the violetlight being inadvertently emitted except when the toothbrush is actuallylocated within the mouth of the user. In another embodiment, the controlcircuitry may alternatively include one more sensors located on thehandle to determine whether the brush head is actually located within auser's mouth.

In one embodiment, an AC or DC signal loop sensor establishes a signalloop through the user's mouth to the user's hand grasping the handle ofthe toothbrush to verify if the toothbrush head is within the user'smouth. If the sensor establishes a signal loop, the light source remainson until the toothbrush head is removed from the user's mouth breakingthe signal loop. Once the signal loop is broken, the light source may beextinguished as soon as the brush head is removed from the mouth.

In another embodiment, the dental hygiene implement uses a capacitivesensor to determine whether the implement is within the user's mouth oroutside of the user's mouth. The capacitive sensor may use a currentloop which detects current flowing through the body of the end user whenthe brush head or bristles are in contact with the mouth and the handleis in contact with the hand.

In another embodiment, the dental hygiene implement uses a capacitivedisplacement sensor to determine whether the implement is within theuser's mouth or outside of the user's mouth. The capacitive displacementsensor can detect change of position of any conductive target such asthe human body.

In another embodiment, the dental hygiene implement uses an inductivesensor to determine whether the implement is within the user's mouth oroutside of the user's mouth. The inductive sensor uses an inductanceloop to measure the proximity of conductors such as the human body.

In another embodiment, the dental hygiene implement uses a passivethermal infrared sensor to determine whether the implement is within theuser's mouth or outside of the user's mouth. The passive thermalinfrared sensor detects the warmth of the human mouth to determinewhether the implement is within the user's mouth.

In another embodiment, the dental hygiene implement uses an activethermal infrared sensor to determine whether the implement is within theuser's mouth or outside of the user's mouth. The active thermal infraredsensor uses a photoelectric sensor that detects reflected IR lightemitted and absorbed by the sensor itself. This could be used to detectproximity inside the mouth.

In another embodiment, the dental hygiene implement uses a passiveoptical sensor to determine whether the implement is within the user'smouth or outside of the user's mouth. The passive optical sensor is alight sensor that triggers the LED when it detects darkness when presentinside the user's mouth. For increased sensitivity to changes in lightintensity, the light sensor may be sensitive to a wavelength at least 50nm different from the LED.

In yet another embodiment, the dental hygiene implement uses a photocellto determine whether the implement is within the user's mouth or outsideof the user's mouth. A photocell is a light sensor that detects thereflection of light from a second light source on the implement when theimplement is turned on. In one embodiment, the photocell may turn on theLED when it detects the reflection of light from a second light sourcewhile in the user's mouth.

In another embodiment, the dental hygiene implement uses an ultrasonicsensor to determine whether the implement is within the user's mouth oroutside of the user's mouth. The ultrasonic sensor may use echo locationto detect the confines of the mouth.

In another embodiment, the dental hygiene implement uses a passiveoptical sensor to determine whether the implement is within the user'smouth or outside of the user's mouth.

In yet another embodiment, the dental hygiene implement uses a magneticsensor to determine whether the implement is within the user's mouth oroutside of the user's mouth. In one embodiment of the present invention,the magnetic sensor may turn on the LED when it detects the proximity ofmetals such as the hemoglobin present in blood.

In yet another embodiment, the dental hygiene implement uses a pressuresensor to determine whether the implement is within the user's mouth oroutside of the user's mouth. In one embodiment, the pressure sensor maybe located under the brush head to detect movement and pressure of thebrush head being pressed against the teeth. The type of pressure sensorsuch may be piezoelectric, capacitive, potentiometric, optical orelectromagnetic. In another embodiment, the pressure sensor may belocated on the handle—detects torque and tension in the handle of thebrush due to brushing action. The pressure sensor could bePiezoelectric, Capacitive, Potentiometric, Optical or Electromagnetic.

In yet another embodiment, the dental hygiene implement uses a moisturesensor to detect a highly moist environment such as the mouth. This canbe accomplished through various types of moisture sensors for example;capacitive or chilled mirror dew point sensors.

Other embodiments of the present invention may include combinations oftwo or more of these sensor types as disclosed above. Furthermore, thesensor examples listed above is not intended to be a complete list ofthe sensors available for use with the present invention. Therefore, thepresent invention is not to be limited to the use of the specificsensors or oral care instruments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by a reading of the DetailedDescription of the Examples of the Invention along with a review of thedrawings, in which:

FIG. 1 shows the completion of a signal loop by a user inserting atoothbrush into his mouth;

FIG. 2 depicts a representative oral care instrument, a toothbrush,illustrating various aspects;

FIG. 3 depicts an alternate embodiment in which the wet bristles of thebrush head are conductive to form a contact for completion of the signalloop;

FIG. 4 shows a toothbrush with conductive metal pads;

FIG. 5 shows a toothbrush with conductive plastic pads;

FIG. 6 is a schematic of an exemplary control circuit;

FIG. 7 is a schematic of an exemplary oral care instrument that has areplaceable head and neck;

FIG. 8 is a schematic of an exemplary oral care instrument that has areplaceable brush head;

FIG. 9 is an exploded view of a toothbrush with a capacitive sensor;

FIG. 10 is a circuit view of the embodiment shown in FIG. 9;

FIG. 11 is a partial cross-sectional view of an embodiment of theinvention where the sensor is a capacitive displacement sensor placed onthe handle;

FIG. 12 is a circuit view of an embodiment of the invention where thesensor is a capacitive displacement sensor;

FIG. 13 is depicts an alternate embodiment where the sensor is aninductive proximity sensor;

FIG. 14 shows an embodiment where the sensor is a passive thermal sensorplaced near the upper portion of the handle of a toothbrush;

FIG. 15 shows an embodiment where two passive thermal sensors are placednear the upper portion of the handle of a toothbrush;

FIG. 16 shows an embodiment where the sensor is a passive thermal sensorplaced on the back of the bristle plate of a toothbrush;

FIG. 17 shows an embodiment where the sensor is an active thermalinfrared sensor placed on the back of the bristle plate of a toothbrush;

FIG. 18 shows an embodiment where the sensor is a passive optical sensorplaced on the back of the bristle plate of a toothbrush;

FIG. 19 shows an embodiment where the sensor is a photocell placed onthe brush head of a toothbrush;

FIG. 20 shows an embodiment where the sensor is an ultrasonic sensorplaced on the brush head of a toothbrush;

FIG. 21 is a partially exploded view of another embodiment of thepresent invention, where the sensor is a pressure sensing system;

FIG. 22 is a side view of a portion of the pressure sensing system ofFIG. 21;

FIG. 23 is a perspective view of the pressure sensing system of FIG. 21;

FIG. 24 is an exploded view of the pressure sensing system of FIG. 21;

FIG. 25 is a side elevational view of a portion of the pressure sensingsystem of FIG. 21;

FIG. 26 is a side elevational view of another portion of the pressuresensing system of FIG. 21;

FIG. 27 is a cross-sectional view of a portion of the pressure sensingsystem of FIG. 21;

FIG. 28 is a schematic drawing showing a circuit according to anotherembodiment of the invention where the sensor is a pressure sensingsystem;

FIG. 29 is a schematic perspective view, in partial cross-section, of atoothbrush having a pressure sensing system according to anotherembodiment of the invention;

FIG. 30 is an enlarged detail view of a portion of the toothbrush shownin FIG. 29;

FIG. 31 is an enlarged detail view, in partial cross-section, of atoothbrush head according to another embodiment of the invention wherethe sensor is a pressure sensing system;

FIG. 32 is an enlarged detail view, in partial cross-section, of atoothbrush head according to another embodiment of the invention wherethe sensor is a pressure sensing system;

FIG. 33 is an enlarged detail view, in partial cross-section, of atoothbrush head according to another embodiment of the invention wherethe sensor is a pressure sensing system;

FIG. 34 is a detail view of the toothbrush head of FIG. 33 taken along507-507;

FIG. 35 is a simplified descriptive view of another embodiment of theinvention where the sensor is a pressure sensing system;

FIG. 36 is a partial fragmentary view of a switch used in the toothbrushshown in FIG. 35, the switch being shown in a first position;

FIG. 37 is a partial fragmentary view of the switch shown in FIG. 36,the switch being shown in a second position;

FIG. 38 is a simplified wiring schematic for the toothbrush shown inFIG. 35;

FIG. 39 is a perspective view of another embodiment of the inventionwhere the sensor is a pressure sensing system including a one-piececompressible portion;

FIG. 40 is a perspective view of another embodiment of the inventionwhere the sensor is a pressure sensing system including a two-piececompressible portion;

FIG. 41 is a partial fragmentary perspective view of another embodimentof the invention;

FIG. 42 is a detail view of a switch shown in FIG. 41;

FIG. 43 is a detail view of the switch shown in FIG. 42, the switchbeing shown in a closed position;

FIG. 44 is a partial fragmentary perspective view of another embodimentof the invention where the oral care instrument is a toothbrush having aHall effect sensor;

FIG. 45 is a partial fragmentary perspective view of a toothbrush inaccordance with another embodiment of the present invention;

FIG. 46 is a partial fragmentary perspective view of another embodimentof the invention;

FIG. 47 is a simplified wiring schematic illustrating an electricalcircuit that can be used with the toothbrush shown in FIG. 46;

FIG. 48 is a partial fragmentary perspective view of another embodimentof the invention;

FIG. 49 is a simplified wiring schematic illustrating a circuit that canbe used with the toothbrush shown in FIG. 48;

FIG. 50 shows a simplified descriptive view of a toothbrush inaccordance with another embodiment of the present invention where thesensor is a pressure sensor;

FIG. 51 shows a simple wiring schematic for the toothbrush shown in FIG.50;

FIG. 52 shows a simple wiring schematic for a toothbrush that includes athree position switch;

FIG. 53 shows a simple wiring schematic for a toothbrush with only oneswitch;

FIG. 54 shows an exploded view of the toothbrush shown in FIG. 50;

FIG. 55 shows an alternative configuration for the contact plates shownin FIG. 54;

FIG. 56 shows the contact plates of FIG. 55 when a force is applied tothe bristle head of the toothbrush;

FIG. 57 shows the contact plates of FIG. 55 when the force applied tothe bristle head exceeds a predetermined level;

FIG. 58 shows a perspective view of a portion of a toothbrush inaccordance with another embodiment of the invention where the sensor isa pressure sensor;

FIG. 59 shows a partially exploded perspective view of a portion of thetoothbrush shown in FIG. 58;

FIG. 60 shows a sectional view of a portion of the toothbrush shown inFIG. 58;

FIG. 61 shows another sectional view of the toothbrush shown in FIG. 58;

FIG. 62 shows a partially exploded perspective view of a portion of atoothbrush in accordance with another embodiment of the invention wherethe sensor is a pressure sensor;

FIG. 63 shows a sectional view of a portion of the toothbrush shown inFIG. 62;

FIG. 64 shows a perspective view of a toothbrush having a one-piececompressible portion in the handle in accordance with another embodimentof the present invention;

FIG. 65 shows a perspective view of a toothbrush having a two-piececompressible portion in the handle in accordance with another embodimentof the present invention;

FIG. 66 shows a simplified descriptive view of a toothbrush inaccordance with another embodiment where the sensor is a pressuresensor;

FIG. 67 shows an enlarged detail of a switch shown in FIG. 66, theswitch being shown in a first position;

FIG. 68 shows the switch from FIG. 67 in a second position;

FIG. 69 shows a simplified descriptive view of a toothbrush inaccordance with another embodiment of the present invention;

FIG. 70 depicts a toothbrush illustrating various aspects of anotherembodiment of the present invention wherein the sensor is a moisturesensor;

FIG. 71 depicts another embodiment of a toothbrush wherein the sensor isa moisture sensor;

FIG. 72 shows an embodiment of the present invention wherein the sensoris an accelerometer;

FIG. 73 shows an embodiment of a toothbrush including a fingerprintsensing module;

FIG. 74 is a flowchart illustrating an embodiment of steps for use of atoothbrush having a fingerprint sensing module and a plurality of LEDstatus indicators; and

FIG. 75 is a simplified schematic of an embodiment of a toothbrushincluding a fingerprint sensing module and a plurality of LED statusindicators.

DETAILED DESCRIPTION OF EXAMPLES OF THE INVENTION

Exposing the mouth to light in the violet and/or blue region of thevisible spectrum, between 400 nm and 500 nm, can be useful for a varietyof purposes, including destroying bacteria and accelerating thewhitening effects of a tooth bleaching agent. However, direct eyeexposure should be limited in order to prevent eye damage. Thus, an aimof the present invention is to determine whether an oral care instrumentis within the user's mouth or outside of the user's mouth. If theinstrument is within the user's mouth, then a light emitting source suchas an LED is turned on to emit light. However, if the instrument isoutside the user's mouth, the LED shuts off to prevent light exposure tothe eyes.

Aspects of the invention are illustrated in the remainder of thisdisclosure with reference to a manual or electric motorized toothbrush,although it is understood that the operation of any number oflight-emitting oral care instruments, together with the associatedadvantageous features and/or beneficial effects described herein, couldlikewise be achieved. Other oral care instruments may include those usedin dental curing lamps, oral flossing implements, and oral surgicalinstruments, etc.

In one embodiment, as shown in FIG. 1, a light-emitting oral careinstrument 100 activates upon the completion of an electrical circuitbetween the brush handle in contact with the user's hand and contact ofthe brush head with the user's mouth.

In the embodiment of the light-emitting toothbrush 100 shown in FIG. 2,the brush head 118 and the handle 114 are injection molded of anelectrically-conductive plastic with a non-conductive hydrophobicplastic spacer 112 located between the brush head 118 and the handle114. The nonconductive plastic spacer 112 electrically insulates thebrush head 118 and the handle 114 from each other. The brush head 118and handle 114 are electrically connected, via a lead 116, to a controlcircuit 110 that can produce a low level electrical signal. While DCcurrent is likely easiest with a battery source, the signal could be AC.The control circuit 110 can include a high sensitivity current sensor,such as Linear Technology LTC1440 Ultralow Power Single/Dual Comparatorwith Reference located on the control circuit 110. That comparator isavailable from Linear Technology Corporation, 1630 McCarthy Blvd.,Milpitas, Calif. 95035-74171(408) 432-1900, linear-tech.com.

Alternatively, the signal loop sensor circuit can be the one seen inFIG. 6, implemented with off the shelf components. An integrated circuit(IC1) shown in FIG. 6 can be a TPS2812 Dual High-Speed Mosfet Driveravailable from Texas Instruments, Inc. of Dallas, Tex. One of the sensorelectrodes 116 is connected through a battery supplying from three totwelve volts, to pins 1-3 and 6 of IC1. The other sensor electrode 115is connected across and adjustment bridge variable resistor R2 and topin 4 of IC1 across resistor R1 to pins 1-3. Pin 4 is tied through Zenerdiode CR1 to pins 1-3. Pin 5 of IC1 is tied as the output to the LEDdriver. When the signal loop through electrodes 115 and 116 iscompleted, the current is sensed in IC1, outputting a signal on pin 5 toactivate the driver for the LED.

Prior art toothbrush sensors were implemented with older bipolartransistor technology and required high currents in the signal loop andhigher voltages, producing undesirable tingling sensations for the user.The preferred signal loop sensor uses ultra-low-power CMOS technology toreduce the detection current threshold to a sub-microampere level ataround one volt of potential difference, preventing any tinglingsensation. Another advantage is an ultra-low battery consumptioncurrent.

A signal loop is formed through the body of the user by holding thebrush handle 114 and placing the brush head 118 or wet bristles of thebrush 113 in contact with the mouth. A voltage across the handle and thebrush head results in a small signal current that flows through the loopand is detected by the current sensor. The current sensor outputs asignal through the control circuit 110 to the LED driver 111, whichdelivers current to the LED 117 within the user's mouth, causing the LED117 to illuminate the mouth of the user. The LED preferably emits shortwave length light in the band between 400-500 nm, more preferably400-450 nm, and more preferably yet of 400-420 nm.

In an alternate embodiment 130 shown in FIG. 3, conductive plastic isused in the part 133 of the brush connecting the bristles 132 to a sheetof conductive plastic 133, instead of the entire brush head.Alternatively, but also possibly in combination, as shown in FIG. 3, thebristles 132 of the brush may also be conductive. When wet bristles 132come in contact with the mouth of the user during normal brushingoperations a circuit is formed via a sense electrode 135 connected tothe control circuit 110, which can be used to detect the completion ofthe electrical signal loop and signals the driver 111 to supplyelectricity to the LED 131. The remainder of the brushhead 134, iscomposed of non-conductive plastic.

Typically when brushing teeth, a user will grasp the handle 114 oftoothbrush 100, apply toothpaste to the bristles 113 and place the brushhead 118 in the mouth and proceed to brush their teeth. While thetoothbrush handle 114 is in contact with the user's hand and the brushhead 118 is located in the mouth of the user, contact between theelectrically conductive plastic of the brush head 118 and mouth of theuser completes the signal loop, enabling a small DC or AC current(sensor current) to be initiated and detected by the control circuit110. The receipt of the sensor current is signaled to the LED driverwhich, in turn, controls illumination of the LED 117, in this case,turns on the LED 117. When contact between the brush head 118 and themouth is broken, i.e., when the brush head 118 is withdrawn from themouth, the signal loop is broken, the flow of sensor current stops, andthe LED 117 is turned off. It is to be appreciated that the sensorcurrent required to control the LED 117 will preferably be in the 10 and100 nanoampere range and would only be detectable with a highsensitivity current meter associated with the control circuitry 110. Dueto the use of such a low electrical current, the user will be safe fromharm and will not be exposed to danger. The galvanic current generatedwhen a person touches a wet metal object is far greater than the currentused in our application, so the current passing through the user's bodyis harmless and imperceptible.

The electronics, i.e. the LED driver and control circuitry 110 areconfigured to regulate or adjust the sensor current so that the brushhead 118 must be in contact with the user's mouth to turn on the LED117. Merely contacting the dry skin from hand to hand will not turn theLED 117 on since the dry hand is not as conductive as the wet mouth.This reduces the possibility of turning the LED 117 on merely byhandling the toothbrush 100 with bare hands and inadvertently activatingthe LED 117 while the brush head 118 is not in the user's mouth.

In a further embodiment of the toothbrush 150 as illustrated in FIG. 4which is similar to the prior embodiment, the brush head and handle 153could be formed from a hydrophobic, nonconductive plastic instead of theelectrically conductive plastic. In this embodiment, electricallyconductive metal pads 151, 152 are located on the exterior surface ofthe toothbrush 150. One or more metal pads 151 are located on the handle112′ and one or more metal pads 152 are located on the brush head. Themetal pads 151 are positioned on the toothbrush 150 for optimal contactwith the skin of the hand and pad 152 is mounted for contact with themouth or bristles of the toothbrush. When the wet tips of the brushbristles are in contact with incisor teeth or mouth and the pad 151 isin contact with the user's hand, an electrical circuit is formed throughthe body of the user. It is to be understood that the metal pads 152 ofthe brush head should be spaced apart from the metal pads 151 of thehandle.

In use, while the metal pads 151 of the toothbrush handle are in contactwith the user's hand and when the brush head 152 is located in the mouthof the user or wet bristles are in contact with any wet portion of themouth or teeth, contact between the metal pads 152 of the brush head andmouth of the user completes a signal loop, enabling a small DC current(sensor current) to be initiated and detected by the control circuit110. The sensed current causes the control circuit to activate the LEDdriver to turn on the LED 126. When contact between the brush head andthe mouth is broken, i.e., when the brush head is withdrawn from themouth, the signal loop is broken, the flow of sensor current stops, andthe control circuit turns off

A further embodiment 160 is shown in FIG. 5. The handle has a portion161 of conductive plastic, and the head has a portion 162 of conductiveplastic. Portion 163 is non-conductive. The conductive plastic areas areconnected internally to circuits as described in connection with FIG. 2and so the toothbrush of FIG. 5 can be used in like manner to thetoothbrush of FIG. 2.

Many electric toothbrushes employ a timer to alert the user of the endof a preset brushing time, for example, two minutes, as recommended bythe American Dental Association. These timer circuits are commonlycombined with vibration or noise to alert the end user to the completionof a recommended brushing period. The signal loop sensor disclosedherein can be combined with such a timing circuit in a manner thatcauses elapsed time to be recorded only when the sensor is activated(i.e. light is on). This would facilitate the assurance that the brushtimer was actually measuring elapsed time in the mouth of the user andnot simply elapsed time of the manual activation of the brush. Thecontrol circuit can also include a timer to turn off the LED at a presettime, such as two minutes, signaling to the user that tooth brushing haslasted two minutes. Other ways to signal the user of the completion oftwo minutes can be substituted.

A conventional make/break switch can be included in one of theconductors 115 or 116 or elsewhere in the electrical circuit, ifdesired. Thus, the signal loop is completed only if the user closes thatswitch AND inserts the toothbrush head into the mouth. This can providea further safety and convenience feature. Alternatively, a make/breakswitch could be located elsewhere in the circuit from the battery, tothe control circuit through the LED driver to LED.

Since the LED will be on only when the light from the LED is safely andeffectively used, the life of a charge on the battery should be longer.

The battery can be rechargeable or replaceable, as will be apparent tothose of ordinary skill in the art.

The brush head and/or neck can be replaceable, as long as thereplacement part has the correct electrical contact and a conductor thatcan reliably connect to a mating conductor in the brush handle. Thedesign can allow the sensor current to flow across the junction of thepermanent part and the replaceable part through either two sheets ofconducting plastic or a metal connector such as a pin connector.Examples are seen in FIGS. 7 and 8.

As seen in FIGS. 7 and 8, a brush handle 146 is provided having thenecessary battery, charging electronics and LED, all self-contained andwater-tightly encapsulated within the handle. The handle includes a stem148 in which the LED 126 is mounted. FIGS. 7 and 8 show two differentembodiments, with the stem 148 in FIG. 7 being longer than the stem 148of FIG. 8. The replaceable brush head 157 has a hollow shaft 154 of aninternal diameter slightly larger than the diameter of the stem 148, sothe stem 148 can be inserted into the hollow shaft 154. The brush headhas an array of bristles 156 and an opening 158 to allow the light fromthe LED 126 to pass toward the teeth as they are brushed by thebristles. Preferably the stem and hollow shaft have complementary,non-circular shapes so that the bristles do not rotate around the stem,but stay in a fixed orientation. When the bristles are spent, the brushhead 157 can be removed from the stem 148 and replaced with a new brushhead. Other appliances appropriate for a tooth whitening brush pattern,light curing of gum infections, tongue scraper, flosser, etc can beconfigured with similarly shaped hollow shafts so they can also bemounted onto the stem 148.

In the embodiment shown in FIG. 7 the plastic of the stem 148 and thehead 157 are made electrically conductive, so that the signal loop canbe completed as the user puts the head 157 (as installed on the stem148) into his or her mouth and grasps the handle 146.

In the embodiment shown in FIG. 8 a conductor in the plastic of the stem148 has an electrical contact 170; the head 157 has an electricalcontact 172 within the shaft 154 positioned to mate with contact 170when the head is mounted on the stem. The signal loop can be completedas the user puts the head 157 (as installed on the stem 148) into his orher mouth and grasps the handle 146.

A further enhancement of the interlock control feature of thistoothbrush can be realized using an AC control signal in place of the DCloop sensor current. A low-frequency 200 Hz to 10 kHz square orsinusoidal waveform AC signal with a peak to peak voltage of no greaterthan 1 V will be applied to the toothbrush handle. This AC signal willbe conducted through the user's body in much the same way as a DCcurrent, as described above. One way to implement this is throughselective tone filtering in which a Controlled Oscillator in the handleputs off a square wave form in the low audio band of 1 to 2 kHz. Anarrow band tone filter only allows one tone to come through in thebrush head. This Selective Tone Filter in the brush head is looking forone certain tone. When it receives that tone, it turns on the LED.

In another embodiment of the present invention, as shown in FIGS. 9 and10, the sensor used to detect whether the oral care instrument 180 iswithin the user's mouth is a capacitive sensor. The oral care instrumentmay be a toothbrush 180 with a battery 186, a LED driver 200, and anon/off switch 202. An electronics ground 204 is located on the handle182 of the brush. A conductive electrode sensing element 206 isinstalled preferably on the brush head 184. A sensor system 210 measuresthe capacitance 216 between the sensing element 206 and the electronicsground 204. A microprocessor/controller 212 determines whether themeasured capacitance 216 is above a threshold value, which indicatesthat the toothbrush 180 is inside the user's mouth. If the measuredcapacitance exceeds the threshold value, then the LED driver 200receives a signal and turns on the LED 214. If the measured capacitancedrops below the threshold value, then the LED driver turns off the LED214.

In yet another embodiment, the sensor of the present invention may be acapacitive displacement sensor. One or more tactile sensors arepreferably placed on the handle portion of the oral care instrument, andmeasure capacitance of a conductive target such as the human body. Asshown in FIG. 11, the oral care instrument is a toothbrush 220 with abattery 222 and tactile sensors 224, 224′ placed on opposing sides ofthe handle 226. A switch 230 is off when in its first position. When auser grips the handle 226 at both tactile sensors 224 and 224′,preferably when the brush head 232 is inserted inside the user's mouth,the capacitive sensor 240 senses an increase in capacitance. As shown inFIG. 12, the capacitive sensor 240 causes switch 230 to move to itssecond position, signaling the LED drive 234 to turn on the LED 236. Anadditional on/off switch 242 operated by the user may be installed ontothe oral care instrument.

In another embodiment of the invention, the sensor is an inductanceproximity sensor which uses a radio frequency loop to sense theproximity of conductors such as the human body. In one embodiment, asshown in FIG. 13, the dental hygiene implement is a toothbrush 245having a brush head 246 and handle 247. In this embodiment, theproximity sensor 248 is on the back of brush head 246. The inductanceproximity sensor 248 is comprised of an LC oscillating circuit with asignal evaluator. The LC oscillating circuit is comprised of a coil anda capacitor that emits a high-frequency electromagnetic alternatingfield at the sensing face of the sensor. When the brush head is insertedinto the user's mouth, Eddy currents are generated that reduces theoscillations within the LC oscillating circuit. The signal evaluatordetects this change in oscillation frequency, and the resultingreduction in oscillations sends a signal to the LED driver to turn onLED 249. When the brush head is removed from the user's mouth, theoscillations from the LC oscillating circuit return to normal and theLED driver turns LED 249 off. Different types of inductor circuits maybe used in other embodiments of the present invention.

In another embodiment of the invention, the sensor is a passive thermalinfrared sensor. The passive thermal infrared sensor may be placedanywhere on an oral care instrument. In the embodiment shown in FIGS. 14and 15, the oral care instrument is a toothbrush 250 with a handle 252and brush head 254. At least one passive thermal infrared sensor 256 isplaced near the upper portion of the handle 252 toward the brush head254. As the user inserts the brush head into the mouth, themicroprocessor 260 detects a change in infrared light as detected by thepassive IR sensor 256. The resulting increase in IR light causes themicroprocessor 260 to turn on LED 262. As the user removes the brushhead out of the mouth, the resulting decrease in IR light sensed by thepassive IR sensor 256 causes the microprocessor 260 to turn off LED 262.

In another embodiment, the passive thermal infrared sensor is placed onthe brush head as opposed to the handle. In the embodiment shown in FIG.16, the passive IR sensor 256 is placed on the back of the bristle plate264. Like the embodiment in FIGS. 14 and 15, if the user places thebrush head in his mouth, then the microprocessor 260 will turn on LED262 due to the increase in IR light as sensed by passive IR sensor 256.As the user removes the brush head out of the mouth, the resultingdecrease in IR light sensed by the passive IR sensor 256 causes themicroprocessor 260 to turn off LED 262. The change in infrared light asthe brush head enters the mouth is understood to be a result of thechange in temperature. Thus, it is understood that the passive IR sensordisclosed herein may be substituted with other means for detectingchanges in temperature.

In another embodiment of the invention, the sensor is an active thermalinfrared. This sensor uses a photoelectric sensor that detects reflectedIR light emitted and absorbed by the sensor itself. This could be usedto detect proximity inside the mouth. The active thermal IR sensor 280is typically comprised of a light source 282 that emits IR light and aphoto diode 284 that detects changes in the sensing environment as theIR emitted from the light source is redirected. In one embodiment, anactive thermal infrared sensor is placed on the brush head 272 of atoothbrush 270. The active thermal infrared sensor may be placed eitheron the front face of the plate with the bristles 276 and LED 286.Alternatively, as shown in the embodiment in FIG. 17, the active thermalinfrared sensor 280 may be placed on the back of the bristle plate 274.If the user places the brush head in his mouth, then the microprocessor290 will turn on LED 286 due to the change in IR light as sensed byphoto diode 284. As the user removes the brush head out of the mouth,the IR light returns to a default value as detected by photo diode 284which causes the microprocessor 290 to turn off LED 286.

In another embodiment of the invention, the sensor is a passive opticalsensor where the darkness caused by inserting the oral care instrumentinto the mouth triggers the short wavelength LED to turn on. FIG. 18shows an embodiment wherein the passive optical sensor is installed on atoothbrush 300. In this embodiment, the passive optical sensor 306 ispreferably on the brush head 302 of the toothbrush. In the embodimentshown in FIG. 18, the passive optical sensor 306 is placed on the backof the bristle plate 304. If the user places the brush head in hismouth, then the microprocessor 310 will turn on LED 312 due to thedecrease in light as sensed by passive optical sensor 306. As the userremoves the brush head out of the mouth, the resulting increase in lightsensed by the passive optical sensor 306 causes the microprocessor 310to turn off LED 312.

In another embodiment of the invention, the sensor is a photocell 314that detects the reflection of light from a second light source 316 onthe oral care instrument. In one embodiment, a photocell is placed onthe brush head 322 of a toothbrush 320. The photocell 314 andaccompanying light source 316 may be placed either on the front face ofthe plate with the bristles 324 and LED 330. Alternatively, as shown inthe embodiment in FIG. 19, the photocell 314 and secondary light source316 may be placed on the back of the bristle plate 326. If the userplaces the brush head in his mouth, then the light emitted by lightsource 316 will reflect and be detected by the photocell 314. As thereflected light is detected by photocell 314, the microprocessor 332will turn on LED 330. As the user removes the brush head out of themouth, the photocell 314 will no longer detect the reflected light whichcauses the microprocessor 332 to turn off LED 330.

In another embodiment of the invention, the sensor is an ultrasonicsensor that emits sound waves and uses echo location to detect whetherthe oral care instrument is within the confines of the mouth. In oneembodiment, an ultrasonic sensor 334 is placed on the brush head 342 ofa toothbrush 340. The ultrasonic sensor 334 may be placed either on thefront face of the plate with the bristles 344 and LED 336.Alternatively, as shown in the embodiment in FIG. 20, the ultrasonicsensor 334 may be placed on the back of the bristle plate 346. If theuser places the brush head 342 in his mouth, then the duration that ittakes for the sound emitted by ultrasonic sensor 334 to be received backwill decrease. The decrease in durational response will cause themicroprocessor 348 will turn on LED 336. As the user removes the brushhead out of the mouth, the duration that it takes for the sound emittedby ultrasonic sensor 334 to be received back will increase causing themicroprocessor 348 to turn off LED 336.

In another embodiment of the invention, the sensor is a pressure sensorunder the brush head that detects movement and pressure of the brushhead being pressed against the teeth. FIG. 21 shows the pressure sensingsystem 410 of the present invention 410 and a toothbrush body referredto generally at 411. Generally, toothbrush body 411 will be a manualtoothbrush. The toothbrush body 411 includes a handle portion 412, whichis configured to be grasped by the hand of the user. In the embodimentshown, handle 412 is approximately 3.75 inches long, while the entiretoothbrush body 411 is approximately 7.5 inches long. In the embodimentshown, toothbrush body 411 is made of a filled nylon, but could be othermaterials as well, including polypropylene and other plastics. Handleportion 412 is in the embodiment shown approximately 0.5 inches wide andapproximately ⅜-inch high. The handle portion 412 is closed about allfour sides and its two ends.

At the distal end of handle 412 is a portion 414 which in the embodimentshown is adapted to receive a hinged member portion 416 of the pressuresensing assembly 410. The remaining portion of the toothbrush body isreferred to at 418, and is generally U-shaped in cross-section, open atthe top. The remaining portion 418 comprises a base 420, two upstandingsides 421, 423 and a forward end wall 426. This arrangement providesrigidity for the toothbrush body. From the receiving portion 414,toothbrush body 411 begins to taper inwardly at both sides over a shortdistance until the width of the toothbrush body is approximately 0.25inches. Over this distance, the top edges of the sides 421, 423toothbrush body are flat for a small distance and then angle downwardlyuntil point 425 on the toothbrush body. Over this distance, base 420angles slightly downwardly. The drawings show this structuralarrangement, in particular FIG. 22.

From point 425 to forward end wall 426, the toothbrush body is flat andis adapted to receive a conventional toothbrush brushhead 432. Thedistance from the lower surface 429 of the flat section 431 to the uppersurface 433 of handle portion 412 is approximately 0.75 inches, whilethe height of the toothbrush body in the flat section 431 isapproximately 0.28 inches.

The sides 421 and 423 and the base 420 over the length of the toothbrushbody from receiving portion 414 to the forward end wall 426 have aplurality of openings 427-427 therethrough. In the embodiment shown,these openings are circular, approximately 0.125 inches in diameter,spaced approximately 0.25-0.35 inches apart. In base 420 of flat section431 is an elongated slot 437, which is discussed in more detail below.The openings could have other shapes and spacing, however. The use ofopenings, with an entirely open top, has several advantages. It allowsfluid to easily escape the brush, without trapping oral tissue in theopenings. This arrangement further permits the use of the hinged armpressure sensing assembly 411 without the use of seals between the armand the body. The openings further are large enough to not only allowrinsing water to move freely in and through the toothbrush body duringcleaning, but also allows the unit to dry out thoroughly between uses.

The pressure sensor assembly 410 is shown in relation to the toothbrushbody 411 in FIG. 21, and in an exploded view by itself in FIG. 24. Twoof the component parts thereof are furthermore shown in more detail inFIGS. 25 and 26. The pressure sensor assembly/system includes a hingedmember 416, an elongated aim 430, a brushhead 432 which includes astriking element 434 extending away from a rear surface 433 of thebrushhead, and a deformable dome element 436, conventionally referred toas a “snappy” member, since it makes a snap-like sound when deformedpast a threshold point. Most round snap domes cannot be moved beyond a“flat” position without turning inside out. The rectangular snap domeshown and described herein can be moved to a “beyond flat” position,thereby providing a longer collapsing distance and greater tactile feel.

Hinged member 416 is attached to toothbrush body 411 at receivingportion 414, by means of a screw 435 or the like. It could also be aquick disconnect arrangement to allow convenient replacement of thebrushhead. Hinged member 416 in the embodiment shown is made frompolypropylene or acetal resin (Delrin) or similar plastic. The hingedmember 416 (FIG. 25) includes a rear portion 438 which is approximatelysquare in the embodiment shown and approximately ⅛-inch thick. Forwardof base portion 438 is a narrow hinge portion 442 which in theembodiment shown is approximately 0.015 inches thick, which issufficiently thin to permit a hinge-like action, and approximatelyone-half inch wide.

Forward of hinge portion 442 is a receiving portion 444, which isapproximately 0.25 inches thick. The receiving portion 444 isapproximately 0.3-0.5 inches wide at hinge portion 442 and tapers toapproximately 0.3 inches at a forward end 45 thereof. The longitudinaledges of the receiving portion 444 are in the embodiment shown rounded.The receiving portion 444 is configured to fit within the toothbrushbody, near a rear end of the remaining open portion 418 thereof. Anoctagonal (in cross-section) central opening 448 extends longitudinallyinward of receiving portion 444 from forward end 445 and receives oneend of an arm 430.

Elongated arm 330 in the embodiment shown (FIG. 24) includes proximaland distal portions 450 and 452, connected by an intermediate rod-likeportion 454. In the embodiment shown, arm 430 is made from stainlesssteel, but other materials could be used as well, such as variousplastic materials. Proximal portion 450 is approximately 0.4 inches longand is configured to snugly fit into opening 448 in receiving portion444 of the hinged member, while distal portion 452 upon which brushhead432 is mounted is approximately 0.5 inches long. The intermediateportion 454 is approximately 1.328 inches long in the embodiment shown.

The arm 430 has a total length of 2.245 inches, because the intermediateportion is arranged such that it angles downwardly between the proximaland distal portions. The distance between the centerlines of theproximal and distal portions is approximately 0.35 inches. The angle ofthe intermediate portion of the embodiment shown is approximately withinthe range of 5°-20°, preferably 15°. The intermediate portion 454 isconfigured to closely follow the portions of the toothbrush body inwhich it fits.

Although the hinged member 416 and arm 430 are shown as two pieces inthe present embodiment, they could be made, i.e. molded, as a singleunit.

Mounted on distal end portion 452 of arm 430 is a brushhead 432.Brushhead 432 includes a base portion 458 and a bristle portion 460which is mounted in base 458 and extends upwardly therefrom inconventional fashion. The bristle portion can take variousconfigurations, including conventional arrangements or specialconfigurations to accomplish particular brushing effects. In thearrangement shown, the tops of the bristles are in approximately thesame plane as the hinge portion 442 of the hinged member to preventin/out brushing forces at the bristle tips from causing turning momentsaround the hinge member and distorting the accuracy of the force sensingsystem. The combination of the hinged member 416, arm 430 and brushhead432 can be replaceable as a unit if desired.

Mounted in the base of the brushhead, approximately central thereof inthe embodiment shown, is a set-screw which is the striking element 434.The set-screw extends through the base portion 458 and below the lowersurface 433 of the brushhead, approximately 0.08 inches in theembodiment shown. The setscrew in the embodiment shown is approximately3/32 inches in diameter and ⅛ inch long and is made from stainlesssteel. Alternatively a bump could be molded into the toothbrush baseportion 458. Further, the hinged element, the arm and the brushheadcould be a single piece. The brushhead 432 could also be made removablefrom the arm portion.

When hinged member 416 is secured to the receiving portion 414 of thetoothbrush body, application of force against the brushhead 432 towardthe toothbrush body will result in the brushhead moving about hingedportion 442 of hinged member 416.

A thin dome element 436 is secured to interior surface of flat section431 of the toothbrush body, directly beneath base portion 458 of thebrushhead. Dome element 436 in the embodiment shown is a conventionalsnap dome member having an obround configuration, similar generally to achild's “cricket” toy. The obround snap dome element 436 is capable ofmoving “beyond flat” when it suddenly collapses due to pressure againstit exceeding a particular value by action of the striking element 434.This is shown by the dotted lines in FIG. 27. The “beyond flat”capability, as discussed above, is important to provide a sufficientcollapsing distance that the user can recognize the collapse of theelement. The snap dome is mounted on a ridge within the brushheadreceiving portion to permit the center portion of the snap dome elementto go beyond flat.

In the embodiment shown, the dome element collapses approximately 1/16inch, and beyond flat by approximately 0.045 inches. The force necessaryto collapse the dome is preferably under 200 grams, since selected forcevalues above this range are generally considered as a threshold forexcessive pressure. Snap dome elements are available with variouscollapse forces.

By default, a switch 490 is in an “off” state. In one embodiment, whenthe snap dome 436 collapses it mechanically triggers the switch 490 toan “on” state. Turning the switch onto its “on” state closes the circuitcontaining battery 496 and causes the LED driver 492 to turn on the LED494. While the snap dome 436 remains collapsed due to the pressureapplied when a user brushes his teeth, the LED 494 remains on. Othertypes of switches may be used, including a magnetic sensor where thestriking element 434 causes a first magnetic plate to come into contactwith a second magnetic plate.

The snap dome is secured to the toothbrush body beneath the brushhead bymeans of an adhesive or tape or a trapping element. Slot 437 (FIG. 23)in the base portion of the toothbrush body extends beneath the snapdome, and prevents the possible damping of the snap dome action due tofluid being trapped beneath the dome when it collapses. The slot allowsthe ready escape of the fluid from the toothbrush body and allows forcomplete rinsing and drying of the toothbrush between uses.

In the embodiment shown, the snap dome element is secured to thetoothbrush body beneath the brushhead and the striking element extendsfrom the brushhead. In another embodiment, the snap dome element couldbe positioned on a lower surface of the brushhead and the strikingelement could be positioned on the toothbrush body beneath thebrushhead.

Other pressure sensors may be used with the present invention.Toothbrush 510 for sensing pressure applied during brushing and forindicating when the pressure exceeds a predetermined value is shown inpartial cross-section in FIG. 29. Toothbrush 510 includes apiezoelectric film 524 disposed within brush head 512 and an indicatorcircuit 530, including LED 534, disposed within handle 508.

Referring to FIG. 30, an enlarged cross-sectional view of brush head 512is shown. Tufts 518 of bristles 506 extend through openings 516 inmember 514 of head 512. Each tuft has a crest end 520 extending outwardfrom opening 516 and a root end 522 disposed beneath opening 516 inmember 514. The length of bristles extending between crest end 520 androot end 522 of tuft 518 has a cross-sectional dimension that is lessthan the cross-sectional dimension of opening 516 so that tuft 518 canmove axially through opening 516 and retract downwardly towardpiezoelectric film 524. The cross-sectional dimension of root end 522 isgreater than the cross-sectional dimension of opening 516, whichinhibits root end 522 from passing through opening 516 and retains tuft518 within head 512.

Piezoelectric film 524 is disposed within head 512 beneath root ends 522of tufts 518 so that film 524 will experience strain when pressure isapplied to tufts 518. When pressure is applied to tufts 518, root ends522 are forced into contact with piezoelectric film 524. The pressureexerted by root ends 522 on film 524 causes a change in the strain offilm 524, which causes film 524 to generate voltage. As is well known inthe piezoelectric art, piezoelectric films carry a permanent dipolemoment that, when the film is at rest, is cancelled out by charges inthe atmosphere. Deforming the film, i.e., applying a force to the filmthat generates a strain, changes the orientation of the polymer backboneof the film, which causes the strength of the dipole to change andgenerates an electrical voltage. If the piezoelectric film comes to restin its deformed position, i.e., the pressure applied is constant and nonew strain is generated, the new dipole will again be cancelled out byatmospheric charges and the voltage will cease. As long as theorientation of the polymer is being changed by application of a varyingdegree of pressure to the film, voltage will be generated.

Referring to FIGS. 28 and 29, indicator circuit 530, located within thehandle 508 of toothbrush 510, senses the voltage generated inpiezoelectric film 524 and determines whether the voltage generated isgreater than a predetermined value, e.g., a value that represents alevel of brushing pressure. If the voltage is greater than thepredetermined value, then indicator circuit 540 turns LED 534 on. If thevoltage drops below the predetermined value, then the indicator circuit540 turns LED 534 off Any circuit capable of receiving a signal from thepiezoelectric film, determining if the signal is greater than apredetermined value, and subsequently turning on the LED 534 can be usedas the indicator circuit. Such circuits can be readily constructed bythose skilled in the art.

One example of a suitable indicator circuit is shown in FIG. 28. Thevoltage generated in piezoelectric film is transferred via lead 536 toan indicator circuit 530 that includes comparator 540 and a single LED534. LED 534 turns on when the output voltage from the piezoelectricfilm (applied to variable input 541 of comparator 540) exceeds thevoltage drop across resistor 538 as applied to reference input 537 ofcomparator 540.

The LED of the indicator circuit is preferably located on the toothbrushin such a way that it is not seen by the user when brushing. Thus, theLED is preferably located at the brush head 512.

Referring to FIG. 31, an alternate embodiment of toothbrush head 542 isshown in which a resiliently deformable membrane material 556 capable ofresilient spot deformation, i.e, a membrane that has highly localizedzones which can be resiliently displaced relative to the rest of themembrane without affecting the zones immediately adjacent to thedisplaced zone, is disposed beneath piezoelectric film 554. Such amembrane material is described, e.g., in U.S. Pat. No. 4,633,542(Taravel), the disclosure of which is hereby incorporated herein byreference.

When the toothbrush is at rest, i.e., when no pressure is applied totuft 548 urging it against piezoelectric film 554, membrane 556 is tautand resiliently biases root end 552 of tuft 548 against member 544. Whenpressure is applied to tuft 548, tuft 548 retracts into contact withpiezoelectric film 554 by sliding through opening 546 and causingresilient spot deformation of membrane 556 at the point where tuft 548is urged against piezoelectric film 554, without displacing the contactzones between the root ends of the respective immediately adjacent tuftsand the membrane. Once the strain is released from the membrane, themembrane material regains its original structure. When the toothbrush isremoved from the oral surface, i.e., the pressure is removed, tufts 548return to their initial position with their respective root ends 552abutting against member 544 by virtue of resilient membrane 556returning to its initial position. Membrane 556 is preferably undertension since tension facilitates this spot deformation.

Membrane 556 is preferably formed from an isotropic elastomeric materialselected for its ability to behave anisotropically in that it gives themembrane the property of being able to exhibit resilient deformation inlocalized spots. The choice of material for the membrane and theappropriate thickness are readily determined by the person skilled inthe art as a function of the mechanical characteristics and, inparticular, the elasticity required for the membrane. Suitable membranematerials include, e.g, natural or synthetic latex type elastomers(e.g., polychloroprenes), natural rubber, and silicones.

The thickness of the membrane in the relaxed state will generally varyin the range of 0.10 mm to less than 1 mm. Such a thickness will enablelocalized or spot resilient deformation with an amplitude of 0.5 mm to 5mm for a force of about 1 Newton (N) to 7.5 N (i.e., about 150grams-force to about 750 gf) applied in a distributed manner over theset of tufts of bristles.

Alternatively, membrane 576 may be disposed above piezoelectric film 584between root ends 582 of tufts 578 and piezoelectric film 584, as shownin FIG. 32.

Referring to FIG. 33, in another embodiment, membrane 666 extends acrossa cavity 638 defined by member 644 in head 612 so as to seal cavity 638.The toothbrush also includes piezoelectric film 664. During assembly ofthe toothbrush membrane 666 is fixed, while taut, to head 612 at theperiphery of cavity 638. Cavity 638 and membrane 666 enclose a cushionof air, the presence of which facilitates vertical spot deformation ofmembrane 666 in response to axial retraction of a tuft of bristles.Member 614, which is made of rigid material, e.g., a plastic material,like the remainder of the brush head, is fixed to the brush head andtogether therewith clamps the membrane in continuous manner all aroundthe periphery of cavity 638. Member 614 may be a separate piece forminga rigid extension of the head or may be integrally molded with the head.

A continuous rim 606 projects substantially perpendicularly from an areanear the perimeter of member 614. A continuous peripheral zone 608 ofmembrane 666 is clamped between the side of head 612 and rim 606 therebyfixing membrane 666 to the head and ensuring that membrane 666, member614 and head 612 are fixed relative to one another. In addition oralternatively, membrane 666 may be affixed to rim 620 around the edge ofcavity 638, e.g., by glue or a heat weld, as shown in FIG. 34.

Any method may be used to fix the periphery of the membrane to member614 or rim 620, provided the portion of the membrane that contacts theroot ends 622 of tufts 618 remains resiliently deformable. Tufts 622retract into and are biased by membrane 666 in the same manner asdiscussed above with reference to FIGS. 31 and 32.

Other embodiments are within the claims and include, for example, anembodiment in which the piezoelectric film extends across a cavity,e.g., the cavity shown in FIG. 33, in the absence of a membrane. Inanother embodiment, the indicator circuit is located external to thetoothbrush.

In another embodiment of the invention, the sensor is a pressure sensorin the neck that detects torque and tension in the neck of the brush dueto brushing action. The pressure sensor could be Piezoelectric,Capacitive, Potentiometric, Optical or Electromagnetic. Such a pressuresensor is disclosed in US 20030205492 to Ferber et al, and is herebyincorporated by reference.

FIG. 35 shows a simplified descriptive view of a light emittingtoothbrush 710 in accordance with the present invention. The toothbrush710 includes a toothbrush body 712 that has a handle portion 713 and abrush head portion 714. Within the brush head portion 714 is lightsource 716. The light sources 716 are powered by a battery 718, andcontrolled by electrical circuitry, or a control circuit 720. Althoughonly one battery 718 is illustrated in FIG. 35, it is contemplated thatmore than one battery may also be used. The toothbrush body 712 includesa flexible portion 722 that facilitates some movement of the brush headportion 714 when a force is applied to the brush head portion 714, forexample, when bristles 724 are applied to an operator's teeth. A switch726, which is configured to activate the light source 716, is actuatedwhen a first predetermined force is applied to the brush head portion714.

The interaction of the switch 726 and the movement of the brush headportion 714 exemplifies one of the benefits of the present invention. Ithas been shown that effective brushing occurs when a force of 2N-3N isapplied in a direction normal to the teeth. When the brushing force issignificantly less than 2N, cleaning of the teeth may not be adequate.When a brushing force of significantly more than 3N is applied to theteeth, unacceptably high levels of enamel abrading may occur.

For example, referring to the toothbrush 10 illustrated in FIG. 35, thebrush head portion 714 moves slightly as the bristles 724 contact anoperator's teeth. As more force is applied, the movement of the brushhead portion 714 will increase. It is contemplated that as the forcereaches the level of a predetermined force, for example, a force ofapproximately 2N, the movement of the brush head portion 714 willactuate the switch 726 and the light source 716 will be activated. Toensure that the brushing force meets the minimal level desired, theswitch 726 may be configured with a spring actuator having a knownstiffness. Thus, the switch 726 could be configured such that it isactuated only when a force of at least 2N is applied to the brush headportion 714. Of course, the predetermined force, or minimum requiredbrushing force, can be changed by configuring the switch 726 with aspring actuator having a different stiffness.

As an alternative to configuring the switch 726 with a spring actuatorto control activation of the light source 716, a load cell, or forcesensor 728 (illustrated in FIG. 38 and discussed in more detail below),can be included in the toothbrush 710 to ensure that the light source716 is activated upon application of the predetermined force.

FIGS. 36-37 illustrate one possible configuration for the switch 726. Asseen in FIG. 36, the switch 726 comprises first and second contactplates 729, 731, and a magnet 733 having a limiting device 735. In FIG.36, the switch 726 is in a first position, configured to preventactivation of the light sources 716. With no force being applied to thebrush head portion 714, the magnet 733 is at a distance (d) from amagnetic contact 737 disposed on the first contact plate 729. Themagnetic contact 37 is separated from the second contact plate 731, suchthat the two contact plates 729, 731 are not electrically connected.

As a force is applied to the brush head portion 714, the magnet 733begins to move toward the two contact plates 729, 731, until theattraction from the magnet 733 causes the magnetic contact 737 to movetoward the magnet 733. The magnetic contact 737 then makes contact withthe second contact plate 731, thereby placing the switch 726 in a secondposition and activating the light sources 716 (see FIG. 37). The switch26 can be configured so that the magnetic contact 737 is impelled towardthe second contact plate 731, only after the first predetermined forcehas been applied to the brush head portion 714.

By adjusting various parameters such as the distance between the contactplates 729, 731, the strength of the magnet, and size of the limitingdevice 735, the predetermined force can be adjusted. Thus, the switch726 can be configured to require different amounts of force to activateor stop the light sources 716.

The toothbrush body 712 has a generally cylindrical shape, though itcould be made in almost any shape desired. For example, the translucentportion 742 could be beveled or faceted to create a prismatic affect asthe emitted light passes through it. The minimal space required by thelight source 716 and the control circuit 720, allows for designflexibility. Indeed, the present invention contemplates the use of moretraditional toothbrush bodies, for example, ones having rectangularcross sections. In addition, the light source need not be an LED, butrather, may be a light bulb. As explained below in conjunction withother embodiments of the invention, the light source is not limited toonly one particular kind—e.g., LED.

In addition to varying the arrangement of the light sources, the patternof light generated by any set of light sources may be varied, dependingon the configuration of the control circuit. For example, the toothbrush710 may be configured with a control circuit that allows the LED tovarying in intensity of the light emitted.

FIG. 38 shows a simple wiring schematic of a circuit 750 that can beused in the embodiment illustrated in FIG. 35. The circuit 750 includesthe battery 718, the switch 726, the LED 730 and the control circuit720. The control circuit 720, includes resistors 752 and an electroniccontrol module (ECM) 758. Any suitable ECM may be used with a controlcircuit such as the control circuit 720, though a Philips 51 LPC is onetype of ECM known to work in this application. As discussed above,activation of the light sources in a light emitting toothbrush, such asthe toothbrush 710, may be controlled by a switch that includes a springhaving a known stiffness. Alternatively, a load cell, such as the forcesensor 728 may be used to sense the force being exerted on the brushhead portion 714, and provide a brush force input signal to the ECM 758.This allows the ECM 758 to appropriately control the LED 730 based onthe brush force input signal. It is readily understood by those skilledin the art that the circuit 50 shown in FIG. 8, represents but one ofmany circuits that can be used with the present invention. For example,a separate power supply, along with capacitive and additional resistiveelements, can be added to the circuit to provide greater control of thepower being delivered to the LED.

The embodiments described thus far have each included a switch that isactuated by a force applied to a brush head portion of a toothbrushbody, such as the brush head portion 714 shown in FIG. 35. Thisconfiguration may be particularly useful when an object of thetoothbrush is to train an operator to apply a proper amount of forceduring brushing. There are however, other ways in which a switch, suchas the switch 726, may be actuated. For example, FIG. 39 shows atoothbrush 764 comprising a toothbrush body 766 that includes a handleportion 768 and a brush head portion 770 including bristles 772. Thehandle portion 768 includes a compressible portion 774 that isconfigured to be compressed when an operator uses the toothbrush 764.The compressible portion 774 comprises a non-rigid material, such as anelastomer. Alternatively, FIG. 40 shows a toothbrush 776 comprising atoothbrush body 778 including a handle portion 780 and a brush headportion 782, including bristles 784. The handle portion 780 includes acompressible portion 786 that comprises a rigid portion 788 surroundedby a non-rigid portion 790. This configuration may provide acompressible portion having greater stiffness than the compressibleportion 774 shown in FIG. 39.

The embodiments shown in FIGS. 39 and 40 have compressible portions 774,786 disposed on the same side of the toothbrush body as the bristles772, 784. Of course, a compressible portion of a toothbrush handleportion may be located virtually anywhere on a toothbrush body, forexample, on a side of the toothbrush body opposite the bristles. FIG. 41shows a toothbrush 792 comprising a toothbrush body 794 including ahandle portion 796 and a brush head portion 798, having bristles 800.The handle portion 796 includes a compressible portion 802 that isdisposed on a side of the toothbrush 792 opposite the bristles 800. Aswitch 804 is disposed in relation to the compressible portion 802 suchthat compressing the compressible portion 802 actuates the switch 804.Actuating the switch 804 activates light source 806 which may be an LEDas described above, or may be a light bulb. The switch 804 is shown indetail in FIGS. 42 and 43. The switch 804 includes a magnet 808, amagnetic plate 810, and a nonmagnetic plate 812. When a force (F) isexerted on the compressible portion 102, the force causes the magnet 808to move in close proximity to the magnetic and nonmagnetic plates 810,812. When the distance between the magnet 808 and the magnetic plate 810drops below a fixed distance 814, the two plates 810, 812 contact eachother (see FIG. 43), thereby activating the light sources 806.

Other types of switches may be used with a toothbrush having acompressible portion, two of which are shown in FIGS. 44 and 45. FIG. 44shows a toothbrush 816 comprising a toothbrush body 818 including ahandle portion 820 and a brush head portion 822, including bristles 824.The handle portion 818 includes a compressible portion 826. A switch 828is disposed in relation to the compressible portion 826 such thatcompressing the compressible portion 826 actuates the switch 828, whichactivates light sources 830. The switch 828 comprises a magnet 832 and aHall effect sensor 834. The magnet 832 is located beneath thecompressible portion 826 such that application of a force (F) to thecompressible portion 826 causes the distance between the magnet 832 andthe Hall effect sensor 834 to decrease. When this distance is smallenough, current flows through the Hall effect sensor 834 and the lightsources 830 are activated.

Another type of switch that can be used in conjunction with acompressible portion on a toothbrush handle is shown in FIG. 45. Atoothbrush 836 comprises a toothbrush body 838 including a handleportion 840 and a brush head portion 842, including bristles 844. Aswitch 846 comprises first and second contact plates 848, 850 disposedin relation to a compressible portion 852 of the handle portion 838 suchthat compressing the compressible portion 852 causes the two contactplates 848, 850 to move closer to each other until they contact, therebyactuating the switch 846 and activating light sources 854.

FIG. 46 illustrates another way by which the light source in atoothbrush may be activated. A toothbrush 854 comprises a toothbrushbody 856 including a handle portion 858 and a brush head portion 860,including bristles 862. The toothbrush 854 includes a sensing device 864which comprises a capacitive sensor 866 attached to a pair of tactilesensors 868, 870 partially disposed on an external portion 871 of thetoothbrush body 856. The presence of an operator's hand on the tactilesensors 868, 870 closes a switch 874 (see FIG. 47) that allows currentto flow from a battery 876 to a control circuit 878 for controllinglight source 880. The control circuit 878 may be configured similarly tothe control circuit 750 shown in FIG. 38, or may have any configurationsuitable to its use in the circuit 872. Thus, the mere presence of anoperator's hand on the tactile sensors 868, 870 causes the light source880 to emit light according to the programming and configuration of thecontrol circuit 878.

The embodiments thus far described include only manual—i.e., notmotorized—toothbrushes. It is important to note that the presentinvention can be easily utilized with motorized electric toothbrushes aswell. FIG. 48 shows a simplified descriptive view of a motorizedelectric toothbrush 882 in accordance with the present invention. Thetoothbrush 882 comprises a toothbrush body 884 including a handleportion 186 and a brush head portion 888. The brush head portion 888includes a bristle head 890. A flexible portion 892 is provided thatfacilitates some movement of the brush head portion 888 when a force isapplied to it. A first switch 894 is disposed on the handle portion 886,and is configured to connect a motor 896 and light source 898 to anelectric source, such as battery 680. When engaged, the motor 896 drivesthe bristle head 890. The first switch 892 has a first position forpreventing activation of the light source 898 and the motor 896, and asecond position for facilitating automatic activation of the lightsource 898 and the motor 896.

A second switch 682 is disposed within the toothbrush body 884. Thesecond switch 682 has a first position for preventing activation of thelight sources 898 and the motor 896, and a second position foractivating the light sources 898 and the motor 896 when the first switchis in the second position. The second switch 682 is placed in the secondposition when a predetermined force is applied to the brush head portion888. The force may be applied during use, when the bristle head 890 isbrought into contact with a user's teeth.

As in the previous embodiments, the predetermined force may be set byusing a spring having a known stiffness. Specifically, such a spring maybe used to resist a force applied to the brush head portion 888. In thisway, the spring force will need to be at least partially overcome—i.e.,a force equal to the predetermined force will need to be applied to thebrush head portion 888—in order to place the second switch 682 in thesecond position.

As an alternative to using a spring to control the predetermined force,a separate load cell, or force sensor 684 may be utilized (see FIG. 49).FIG. 49 shows a simple wiring schematic of a circuit 686 that can beused with a motorized toothbrush 882. As shown in FIG. 19, the lightsource 898 comprises LED 688 and is controlled by electrical circuitry,or a control circuit 694. The control circuit 694 includes resistor 698and an electronic control module (ECM) 699.

Another useable pressure sensor is disclosed in US2003/0135940 to Lev etal. FIG. 50 shows a simplified descriptive side view of a motorizedelectric toothbrush 1010 in accordance with another embodiment of thepresent invention. A first switch 1012, located in a handle portion1013, has a first or “off” position, and a second or “automatic”position, which places the toothbrush 1010 in an automatic mode. Whilethe toothbrush 1010 is in the automatic mode, a LED 1015 is engaged onlywhen a force (F) is exerted on a removable head portion 1016. Thisoccurs when a bristle head 1018 sufficiently contacts an operator'steeth. As used here and throughout, the term “sufficiently contacts”implies a contact that is sufficient to cause a slight movement of atleast a part of the removable head portion 1016 in the direction of theforce. The force exerted by an operator (a user of the toothbrush)during normal brushing typically constitutes a sufficient contact. Thus,as the user begins brushing, a second switch 1020 automatically movesfrom a first position to a second position, an electric circuit iscompleted, and current flows from a battery 1022 to the LED driver 1024that regulates and transmits power to LED 1015.

FIG. 51 shows a simple wiring schematic 1026 of a circuit for thetoothbrush 1010 shown in FIG. 50. The LED driver 1024 is electricallyconnected between an electric source (the battery 1022) and the firstswitch 1012. When the first switch 1012 is in the first, or “off”position, the circuit 1028 is open and there is no voltage across LEDdriver 1024. When the first switch 1012 is in the second, or “automatic”position, control of the current flow to LED driver 1024 is transferredto the second switch 1020. While the toothbrush 1010 is in the automaticmode, the LED driver 1024 is only engaged when a force (such as (F)shown in FIG. 1) is applied to the bristle head 1018. An exception tothis occurs when the toothbrush is programmed with a “delayed off”feature, discussed in more detail below. With the delayed off feature,the LED 1015 continues to operate for a short time after the force isremoved from the bristle head 1018.

A number of alternative electrical circuits can be used with the presentinvention, two of which are shown in FIGS. 52 and 53. In FIG. 52, awiring schematic 1026′ shows a LED driver 1024′ wired between a battery1022′ and a first switch 1012′. The first switch 1012′ is a threeposition switch, having a first position in which circuits 1028′, 1030are both open. While the first switch 1012′ is in the first position, nocurrent can flow to the LED driver 1024′, and the LED 1015 remains off.The first switch 1012′ has a second position in which control of thecurrent flow to LED driver 1024′ is transferred to a second switch1020′. When the second switch 1020′ is in a first position, the circuit1028′ is open, and LED 1015 remains off. When a force is applied to abristle head of the toothbrush, the second switch 1020′ automaticallymoves to a second position such that the circuit 1028′ is closed and theLED driver 1024′ is engaged. The first switch 1012′ also has a thirdposition, in which the circuit 1030 is closed, and the toothbrushoperates continuously.

Yet another wiring configuration is illustrated in the wiring schematic1026” shown in FIG. 53. In this configuration, there is only one switch1020″ to control the flow of current from a battery 1022″ to a LEDdriver 1024″. When the switch 1020″ is in a first position, circuit1028″ is open, thereby preventing the LED 1015 from turning on. When theswitch 1020″ is in a second position, the circuit 1028″ is closed andcurrent flows to LED driver 1024″. As in the previous wiringconfigurations, the switch 1020″ automatically moves from the firstposition to the second position when a force is applied to a bristlehead of the toothbrush. As described above, each of the switches 1020,1020′, and 1020″ “automatically” moves from a first position to a secondposition when the toothbrush is used by an operator. This implies thatthe user need not manually place the switch in the second position.Rather, the contact between the user's teeth and the bristle headautomatically places the switch 1020, 1020′, or 1020″ in the secondposition.

Toothbrushes in accordance with these embodiments can be configured suchthat applying a force to the handle portion, rather than the bristlehead, effects operation of the LED 1015 when it is in the automaticmode. For example, any of the switches 1020, 1020′, 1020″ can bepositioned within the handle portion 1013 of the toothbrush 1010, shownin FIG. 1. In such a case, the switch may be automatically moved fromthe first position to the second position not by a force applied to thebristle head 1018, but rather, by a force applied to some part of thehandle portion 1013. Embodiments of the invention utilizing this featureare described in more detail below.

Each of the wiring configurations shown in FIGS. 51-53 allow atoothbrush to be used in an automatic mode. That is, the toothbrushmotor is engaged whenever a force is applied to that portion of thetoothbrush that contains the switch 1020, 1020′, or 1020″. Thisfacilitates ease of use, eliminating the need to operate a typicalbutton switch after the bristle head is placed in the user's mouth.Another advantage of such a configuration is that a consumer can engagethe toothbrush motor while the toothbrush is still packaged—i.e., priorto sale. In this way, the consumer can evaluate the operation of thetoothbrush before purchase. Some prior art toothbrushes have amulti-function switch configured such that the consumer operates thetoothbrush in the package using one activation mode, then operates thetoothbrush during normal use in another activation mode. Such is not thecase with the present invention, which affords the consumer theopportunity to activate the toothbrush in the package substantially asit will be activated during normal use. In today's consumer savvyenvironment, this feature provides another advantage over prior arttoothbrushes.

FIG. 52 shows an exploded view of the electric toothbrush 1010 inaccordance with another embodiment. The toothbrush 1010 includes thehandle portion 1013 and the removable head portion 1016, which is shownhaving first and second housing elements 1032, 1034. The handle portion1013 will usually be made from a polymeric material, and may be opaque,clear, or translucent. When the handle portion 1013 is clear ortranslucent, the toothbrush operator may see the movement of some of thetoothbrush components when the motor 1014 is engaged. In addition,aesthetically pleasing features such as flashing lights (not shown) canbe added to the components within the handle portion 1013 to augment thevisual appearance. The removable head portion 1016 also includes a shaft1036 that on one end has a pinion carrier 1038 and on the other a yoke1040 configured to attach to a drive shaft 1042. A pinion 1044 isattached to the bristle head 1018 with a threaded fastener 1046 and awasher 1048. The pinion 1044 interfaces with a rack 1050, only a portionof which is visible through an opening 1052 in the first housing element1032. Also included in the removable head portion 1016 is a snap ring1054 that is manufactured in different colors such that removable brushheads belonging to different users can have different colored snap ringsfor easy identification.

This embodiment includes a rocker element 1056, which serves a number offunctions. First, it contains clips 1058 (only one of which is visiblein this view) that help secure the removable head portion 1016 to thehandle portion 1013. In addition, trunnions 1060 (only one of which isvisible), rotate in apertures 1062 thereby allowing the rocker element1056 to pivot as force is applied to the removable head portion 1016. Asthe rocker element 1056 pivots about the trunnions 1060, a pin 1064moves within a slot 1066. The slot 1066 is located in a first casingportion 1068 which also contains one of the apertures 1062 in which oneof the trunnions 1060 rotates. Also located in the first casing portion1068 is the first switch 1020, which comprises first and second contactplates 1070, 1072. As noted above, the first switch 1020 is optional(see FIG. 53), in which case, the toothbrush 1010 will always be in theautomatic mode.

The contact plates 1070, 1072 are attached to the first casing portion1068 in such a way that movement of the pin 1064 within the slot 1066selectively causes the contact plates 1070, 1072 to contact each otherand electrically connect. Electrically connecting the contact plates1070, 1072 places the second switch 1020 is in the second position. Thismeans that when the toothbrush 1010 is in the automatic mode ofoperation—i.e., when the first switch 1012 is in the secondposition—electrical connection of the contact plates 1070, 1072 engagesthe LED driver 1024 and causes LED 1015 to turn on. Thus, when thetoothbrush 1010 is in the automatic mode of operation, sufficientcontact of the bristle head 1018 with the user's teeth will cause aslight deflection of the removable head portion 1016. This in turncauses the rocker element 1056 to pivot on its trunnions 1060, therebymoving the pin 1064 within the slot 1066. When the pin 1064 causeselectrical connection of the contact plates 1070, 1072, the LED driver1024 is engaged without the user having to manually actuate anyswitches. Hence, turning on of LED 1015 is “automatic”. The contactplate 1070 also acts like a spring, so that when the bristle head 1018is not in contact with the user's teeth, the contact plate 1070 pushesagainst the pin 1064 and biases away from the contact plate 1072. Thus,the second switch 1020 returns to the first position when the bristlehead 1018 is no longer in contact with the user's teeth.

Although the second switch 1020 returns to the first position when thebristle head 1018 is no longer in contact with the user's teeth, the LEDdriver 1024 may not immediately disengage. The action of the LED driver1024 in this situation is dependent upon the configuration of a printedcircuit (PC) board 1074. The PC board 1074 is an electronic controllerthat controls the electrical components of the toothbrush 1010. The PCboard 1074 can be configured such that the LED driver 1024 continues tooperate for a finite time after the second switch 1020 is moved from thesecond position to the first position. The finite time can be a veryshort interval, perhaps as little as a fraction of a second. Thisfeature may be useful when the bristle head 1018 momentarily disengagescontact with the user's teeth during normal brushing. During the shortinterval, until the time the bristle head 1018 is again in contact withthe user's teeth, the LED driver 1024 will continue to run.

Although the wires are removed from this figure for clarity, the simplewiring involved in the present invention is easily understood by oneskilled in the art. The PC board 1074 is wired to the motor 1014 atterminals 1076, 1078. Similarly, battery terminals 1080, 1082 are wiredto the PC board 1074 through spring terminals 1084, 1086. The PC board1074 can also be configured to control other functions in addition tothe “delayed off” feature. For example, the PC board 1074 may not onlycontrol the delay of turning on/off LED 1015, but also the intensity ofLED 1015 output. In addition, if indicator lights are used inconjunction with a transparent or translucent cover, as described above,the PC board 1074 can be configured to control the colors, duration, andsequence of such lights. In addition, the PC board 1074 can beconfigured to control sound elements, either alone, or in combinationwith the LED or indicator lights.

The first switch 1012 includes a switch cover 1088 and a switch button1090. When an operator presses the switch cover 1088 the switch button1090 contacts an electrical component 1092 of the PC board 1074, therebyplacing the switch 1012 in the second position. Further pressing of theswitch cover 1088 toggles the switch 1012 between the first and secondpositions. The handle portion 1013 also includes a drive shaft seal 1094and a seal support 1096. The drive shaft seal 1094 helps to ensure thatfluid does not reach the electrical components of the toothbrush 1010.The PC board 1074 includes an indicator LED 1098 that is visible to auser through a translucent cover 1100. The indicator LED 1098 may beused to indicate when the first switch 1012 is in the secondposition—i.e., when the toothbrush 1010 is in the automatic mode—or maybe used to indicate when the battery 1022 is being charged. The battery1022 is held in place by an end cap 1102 that is provided with an 0-ringseal 1104 to further ensure that fluids do not reach the electricalcomponents of the toothbrush 1010. Also included in the handle portion1013 is a seat element 1106 that allows the toothbrush 1010 to be laidon a flat surface such that the bristle head 1018 remains pointingupward. This helps to keep the toothbrush 1010 stationary on a surfacethat is not level, and keeps the bristle head 1018 from contacting thesurface. Aesthetic features 1108 are added to enhance the visual appealof the toothbrush 1010.

The sensors described in these embodiments may be used in any type ofdental hygiene implement. In the embodiments shown in FIGS. 54, 58-60,the dental hygiene implement is a motorized toothbrush. Thereciprocating movement of the drive shaft 1042 is guided by a bushing1108. The actual movement of the drive shaft 1042 resembles a typicalslider crank mechanism. The motor 1014 has a rotating motor shaft 1110that has a spur gear 1112 attached to it. The spur gear 1112 intermesheswith and rotates a ring gear 1114 that has integrally attached to it acam 1116. The ring gear 1114 and the cam 1116 are held in a secondcasing portion 1118 with a pin 1120. The cam 1116 rotates within a camfollower 1122 that is attached to the drive shaft 1042. Thus, therotational motion of the motor shaft 1110 is translated intoreciprocating motion of the drive shaft 1042. When the removable headportion 1016 is attached to the handle portion 1013, the yoke 1040connects to a head 1124 on the drive shaft 1042 such that the shaft 1036reciprocates along with the drive shaft 1042. This in turn moves thepinion 1044 along the rack 1050 which causes the bristle head 1018 totranslate and rotate simultaneously.

An alternative configuration for the second switch 1020 is shown inFIGS. 55-57. This configuration provides for automatically stoppingoperation of LED 1015 on the toothbrush when the force on the bristlehead in response to contact with the operator's teeth exceeds apredetermined level. FIG. 55 shows a portion of a rocker element 1101that pivots about trunnions 1103 (only one of which is visible). A firstcontact plate 1105 is attached to the rocker element 1101 with afastener 1107. A second contact plate 1109 is attached to a casing withanother fastener 1107, a portion of the casing being shown as 1111. Thecasing has a stop block 1113 integrally formed therewith. The rockerelement 1101 includes an electrically conductive contact pad 1115, whichis an option that can be used when the first switch is a three-positionswitch (see FIG. 51). As illustrated in FIG. 55, the contact pad 1115 iselectrically connected to the contact plate 1105, and when athree-position first switch is used, the contact pad 1115 will be wiredto the first switch. Thus, when the first switch is in the thirdposition, the toothbrush motor (such as 1014 shown in FIG. 51) willoperate continuously. A spring 1117 is disposed between the rockerelement 1101 and another portion of the casing (not shown), and biasesthe first contact plate 1105 away from the second contact plate 1109.

FIG. 56 is illustrative of automatic operation of the toothbrush. As thebristle head contacts the operator's teeth, the rocker element 1101pivots about the trunnions 1103, thereby electrically connecting thecontact plates 1105, 1109. As illustrated in FIGS. 55-57, the firstcontact plate 1105 is wired to the LED driver, and the second contactplate 1109 is wired to the battery. Thus, when the first switch is inthe second position, or when there is only one switch (see FIG. 52), theelectrical connection of the contact plates 1105, 1109 causes operationof LED 1015 on the toothbrush. If the operator continues to apply forceto the bristle head beyond a predetermined level, the first contactplate 1105 will impinge on stop block 1113, but the rocker element 1101will continue to pivot (see FIG. 57). A protrusion 1119 on the rockerelement 1101 then contacts the second contact plate 1109 and pushes itaway from the first contact plate 1105. This opens an electric circuitand turns off the LED 1015. Even if the toothbrush has a “continuous on”feature, the LED 1015 will still turn off when the first contact plate1105 impinges on the stop block 1113. This is because the contact pad1115 will no longer be in contact with the first contact plate 1105. Thepredetermined level at which the LED 1015 turns off can be easilyadjusted by changing the spring 1117, the size of the stop block 1113,or the size of the protrusion 1119.

FIGS. 58-62 show portions of a toothbrush 1126 in accordance withanother embodiment of the present invention. The toothbrush 1126comprises a handle portion 1128 that includes a first housing 1130, anda removable head portion 1132 that includes a bristle head 1134 and asecond housing 1136. This includes a shaft and a pinion which interfaceswith a rack to drive the bristle head 1134. A yoke 1138, seen in FIGS.60 and 61, connects to a head 1140 of a drive shaft 1142 whichreciprocates when a motor (not shown) is engaged. A seal 1144 isdisposed around the drive shaft 1142 to protect the electricalcomponents of the toothbrush 1126 from contamination by fluids.

As in the previous embodiment, the toothbrush 1126 includes an automaticmode of operation. To facilitate the automatic mode of operation, thetoothbrush 1126 has a first switch (not shown) that is configured as inthe previous embodiment. A second switch 1146, seen in FIGS. 59 and 61,includes a contact plate 1148 having legs 1150 and a contact rod 1152.The contact plate 1148 and the contact rod 1152 are disposed within thehandle portion 1128 and are covered by a seal 1154. Similar to thecontact plates 1070, 1072 used in the first embodiment, the contactplate 1148 and the contact rod 1152 are wired to a PC board (not shown).

The method by which the removable head portion 1132 attaches to thehandle portion 1128 is also different from the first embodiment. Anadaptor 1156, seen in FIGS. 60 and 61, is located inside the housing1136 of the removable head portion 1132, and snaps into recesses 1157 inthe handle portion 1128, (see FIG. 60). This attachment allows theremovable head portion 1132 to be securely attached to the handleportion 1128, and at the same time allows the head portion 1132 to pivotin relation to the handle portion 1128 when the bristle head 1134sufficiently contacts the user's teeth. As consistently used throughoutthe various embodiments, “sufficiently contacts” merely implies acontact that is sufficient to cause a slight movement of at least a partof the removable head portion 1132.

As the removable head portion 1132 undergoes the slight pivoting motioncaused by contact with the user's teeth, a projection 1158 pushes into anotch 1159 in the seal 1154. As the projection 1158 moves into the notch1159, it pushes the seal 1154 against the contact plate 1148. With thelegs 1150 held stationary, the contact plate 1148 deflects in aspring-like fashion until it contacts the contact rod 1152. This placesthe second switch 1146 in the second position, and enables LED 1015 toturn on when it is in the automatic mode. The spring-like deflection ofthe contact plate 1148 also acts to bias it away from the contact rod1152, to turn off LED 1015 when the bristle head is not in contact withthe user's teeth. As in the previous embodiment, the PC board can beconfigured such that the LED 1015 does not disengage immediately, butrather, remains engaged for a short time after the bristle head isremoved from the user's teeth.

Although both of the embodiments described above have a two-positionfirst switch, as illustrated schematically in FIG. 51, a three-positionswitch (as shown in FIG. 52) can be used. Alternatively, the firstswitch can be eliminated, as in FIG. 53, so that the toothbrush isalways in the automatic mode. The two toothbrushes described aboveinclude removable brush head portions; however, either can be made witha non-removable brush head portion. In fact, any of the embodimentsdescribed herein can be made with a non-removable brush head portion,which may be particularly well suited to disposable toothbrush designs.

Portions of a third embodiment of the present invention are shown inFIGS. 62 and 63. In this embodiment, a toothbrush 1160 includes a handleportion 1162 that has a first housing 1163, and a removable head portion1164 that has a second housing 1165 and a bristle head (not shown). Asin the previous embodiments, the toothbrush 1160 includes a first switch(not shown) having a first, or “off” position that prevents the LED 1015from turning on, and a second, or “automatic” position that allows theLED 1015 to function in an automatic mode. A second switch 1166comprises first and second stationary contact plates 1168, 1170, and athird contact plate 1172. The removable head portion 1164 includes aprojection 1174 that fits into a notch 1176 in the first housing 1163 ofthe handle portion 1162.

The removable head portion 1164 attaches to the handle portion 1162 atsnaps 1178. This connection allows the removable head portion 1164 besecurely attached to the handle portion 1162, and at the same timeallows the head portion 1164 to pivot in relation to the handle portion1162 when a bristle head (not shown) sufficiently contacts the user'steeth. As the removable head portion 1164 pivots, the third contactplate 1172 contacts, and thereby electrically connects, the stationarycontact plates 1168, 1170. This places the second switch 1166 in thesecond position, and causes LED 1015 to turn on when it is in theautomatic mode. The projection 1174 also acts as a spring as theremovable head portion 1164 pivots, thereby keeping the third plate 1172biased away from the stationary plates 1168, 1170 when the bristle headis not in contact with the user's teeth.

In each of the embodiments described above, the second switch wasautomatically moved from the first position to the second position whena force was applied to the bristle head. Specifically, a force on thebristle head in response to its contact with the operator's teeth causedthe second switch to move to the second position and the motor wasengaged. As previously noted however, the second switch need not beactivated by a force on the bristle head. Rather, the second, switch maybe located such that it is automatically placed in the second positionwhen the user grips the handle portion. One way to accomplish this is toprovide the handle portion with a compressible portion, and dispose thesecond switch in relation to the compressible portion such thatcompressing the compressible portion moves the second switch from thefirst position to the second position, thereby turning on LED 1015.

FIGS. 64 and 65 illustrate two embodiments of toothbrushes havingdifferently configured handle portions. FIG. 64 illustrates a toothbrush1180 having a compressible portion 1182. The compressible portion 1182can be molded integrally with toothbrush handle housing 1184, or may beattached in a separate operation. The compressible portion 1182 istypically made from a polymeric material that deflects when thetoothbrush is used in a normal brushing operation. The handle housing1184 may be configured with a relatively small, or a relatively largecompressible portion. In this embodiment, the compressible portion 1182occupies a large area of the handle housing 1184, thereby helping toensure that users having different gripping preferences will beaccommodated.

FIG. 65 illustrates a toothbrush 1186 having a compressible portion 1188located in a housing 1190 of a handle portion 1192. In this embodiment,the compressible portion 1188 includes a rigid portion 1194 and anon-rigid portion 1196. When a user compresses the compressible portion1188, the non-rigid portion deflects, thereby moving a switch (notshown) from a first position to a second position to turn on LED 1015.Having a two-piece compressible portion such as 1188 not only changesthe look, but also the feel of the toothbrush when compared to atoothbrush having a single piece compressible portion. Thus, thedesigner is allowed flexibility with regard to both form and function.

FIG. 66 shows a toothbrush 1198 that includes a removable head portion1200 and a handle portion 1202. The handle portion 1202 includes a firstswitch 1204 which has first and second positions for respectivelyturning off and on LED 1015. The handle portion 1202 includes a handlehousing 1206 that has a compressible portion 1208. Disposed within thehandle portion 1202 in close proximity to the compressible portion 1208,is a second switch 1210, shown in detail in FIG. 67.

The switch 1210 shown in FIG. 67 includes a magnet 1212, a magneticplate 1214, and a non-magnetic plate 1216. When the first switch 1204 isin the second position, motorized operation of the toothbrush 1198occurs only when a force (F) is exerted on the compressible portion1208. This force causes the magnet 1212 to move in close proximity tothe magnetic and non-magnetic plates 1214, 1216. When the distancebetween the magnet 1212 and the magnetic plate 1214 drops below a fixeddistance 1218, the two plates 1214, 1216 contact each other (see FIG.68). When the first switch 1204 is in the second position, and the twoplates 1214, 1216 contact each other, the LED driver is engaged (notshown), thereby causing LED 1215 to turn on.

FIG. 69 shows another embodiment of a toothbrush 1222. The toothbrush1222 has a handle portion 1224 and a removable head portion 1226. Thehandle portion 1224 includes a compressible portion 1228. In thisembodiment, toothbrush 1222 only has one switch 1229 which comprises amagnet 1230 and a Hall effect sensor 1232. The magnet 1230 is locatedbeneath the compressible portion 1228, and application of force (F) tothe compressible portion 1228 causes the distance between the magnet1230 and the Hall effect sensor 1232 to decrease. When this distance issmall enough, current flows through the Hall effect sensor 1232, and LED1215 turns on.

In another embodiment of the invention, the sensor is a moisturedetection—uses a moisture sensor to detect a highly moist environmentsuch as the mouth. This can be accomplished through various types ofmoisture sensors for example; capacitive or chilled mirror dew pointsensors. Such a sensor is disclosed in US 2009/0087813 to Cai et al, andhereby incorporated by reference.

These motion sensor embodiments of the present invention relate to abio-active oral care instrument, having the ability to active an LEDautomatically, when the instrument or a portion thereof is exposed toone or more conditions, such as the ambient electrical conductivity,existing in the oral environment. Other conditions and combinations ofconditions, such as pH, temperature, solute concentrations, etc. couldlikewise be detected and used as the basis for automatic operation.Furthermore, aspects of these embodiments are illustrated in theremainder of this disclosure with reference to an electric motorizedtoothbrush, although it is understood that the operation of any numberof oral care instruments, together with the associated advantageousfeatures and/or beneficial effects described herein, could likewise beachieved. Other oral care instruments, for example, include those usedin dental drilling, polishing, and grinding; oral suction instruments,oral surgical instruments; and other instruments used in the oral cavitywhich are powered by motorized devices and especially electricaldevices.

The representative toothbrush illustrated in FIG. 70 has a handle 901and a head 905 carrying one or more cleaning elements, which aredepicted in FIG. 70 as a plurality of bristles 906. Also illustrated isa neck 904 located between, and connecting, handle 901 and head 905. Thebristles 906, as shown, form clusters that are anchored to the head 905and provide a profiled brushing surface with their free ends. Otherbristle configurations are of course possible, as well asremovable/exchangeable bristle clusters. Different types of cleaningelements (e.g., elastomeric wipers, nodules, pointed structures, etc.)may also be carried on head 905 instead of, or in addition to, bristles.

The neck 904 is provided with electrical conducting elements 907 (e.g.,an anode and a cathode) that are exposed to the exterior surface of thetoothbrush. In other embodiments, the electrical conducting elements 907can be located on the head 905, for example on the surface opposite thatwhich carries bristles 906. The use of electrical conducting elements907 on different parts of the toothbrush is also possible. A pluralityof electrical conducting elements 907 can also be incorporated invarious positions to activate the instrument in the event thatsufficient electrical conductivity is established between any givenpair(s) of electrical conducting elements 907 located at any desiredposition. Integrated in the region of the neck 904 which is adjacent tothe head 905 is a LED driver 911 that is operably connected to LED 960.The motorized device 911 is operably connected, via electricalconnections 934 in the neck 904 to a power source (e.g., a battery, notshown), which may be accommodated in the handle 901. Operably connectedand operably connectable refer to the ability of the electricalconnections, or other elements, to readily foam an electrical circuit(e.g., when a switch is depressed or when a power source is connected orinstalled). Operably connected and operably connectable may also referto the ability of mechanical components to be connected to one anotherin such a manner as to allow or provide for physical movement of one ormore elements. The LED driver may be alternatively incorporated in thehead 905 or handle 901 of the toothbrush. In representative embodiments,electrical connections 934 may be metal wire or electrically conductiveplastic tracks.

In particular embodiments where the toothbrush uses a vibratory device,it will have a vibratory element which can be in the form of aneccentric, which produces mechanical vibrations and can be rotated aboutan axis located in the longitudinal direction of the toothbrush.Alternatively, instead of an eccentric which can be driven in rotation,it would also be possible to have a vibratory element which can bedriven in a translational manner Otherwise, the bristle-carrying head905 can be arranged such that it can be moved in relation to the neck904 in order for the latter, in the case of vibrations produced bymotorized device 911, to move in relation to the rest of the toothbrush.

As shown, also accommodated in the handle 901 is a sheath or sleeve 920which extends in the longitudinal direction of the handle 901 and ismade of electrically conductive material. In the representativeembodiment shown, both the handle 901 and the sleeve 920 are open to therear, thus forming a cavity 921 which can be closed from the rear by aclosure part 922 and into which it is possible to insert a battery, suchas a commercially available, non-rechargeable cylindrical battery, witha defined voltage (e.g. 1.5 V), as the power or voltage source for LEDdriver 911. It would also be possible, however, for a button cell or fora rechargeable storage batter to be used as the power source. Anexternal power source such as a conventional electrical outlet or acombination of voltage sources may be employed as the power source.

Also shown in the particular illustrative embodiment of FIG. 70 is aspring contact 929 for a positive pole of a battery (not shown), whichis fitted in the sleeve 920, on a transverse wall 92S, and iselectrically connected to the LED driver 911 through the electricalconnections 934 and switch 932, which is installed in the sleeve 920 andcan be actuated from the outside of the handle 901. Switch 932 may alsobe, for example, a magnetic switch pulse switch or a pulse switcharranged on a printed circuit board with further electronic componentsthat store the switching state. In other embodiments, closure part 922can itself act as a switch, such that electrical contact between thepower source and LED driver 911 is established or interrupted by turningclosure part 922 to alter the position of contact surface 922 b relativeto the negative pole of a battery.

It is to be appreciated, as discussed in greater detail below, thatswitch 932 is not necessary due to the ability of the toothbrush to turnon automatically when in the user's mouth. In some embodiments,therefore, the toothbrush can be “switchless” or “buttonless.”

Switch 932 may be depressed or adjusted by the user to effect a numberof operating modes. For example, in “on” and “off” positions orsettings, electrical communication or an electrical circuit between thepower source and LED driver 911 may be continually established orcontinually interrupted, respectively. In the former case, for example,the electrical conducting elements 907 may be bypassed to allowcontinuous operation of motorized device 911, regardless of the presenceof a conductive medium between electrical conducting elements 907.Switch 932 may also have a position corresponding to conditionalcompletion of the electrical circuit.

Also as shown in FIG. 70, the closure part 922 is provided with athreaded stub 922 a made of an electrically conductive material, whichmay be the same material (e.g., a metal such as copper or a conductiveplastic) used for the electrical conducting elements 907, electricalconnections 934, spring contact 929, and/or sleeve 920. Closure part 922can be screwed into the handle 901 and/or into the sleeve 920 by way ofsaid threaded stub 922 a. The threaded stub 922 a is provided with acontact surface 922 b which, with the closure part 922 screwed in, comesinto abutment against the negative pole of a battery (not shown) wheninserted into the sleeve 920. During operation of the motorizedtoothbrush, this negative pole is electrically connected to LED driver911 via the threaded stub 922 a, the sleeve 920 itself, and electricalconnections 934 connecting sleeve 920 to LED driver 911. It would alsobe possible, instead of through the use of sleeve 920, for the powerfrom the negative pole to be transmitted in some other way, for exampleusing wires or electrically conductive plastic tracks. Instead of therear closure part 922 being screwed to the handle 901, it would, ofcourse, also be possible to have some other type of releasableconnection (e.g. plug-in connection, bayonet connection, etc.) and acorresponding configuration of the contact part interacting with thenegative pole of the battery.

One representative characteristic of the oral environment which differssignificantly from the surrounding or ambient “non-use” environment iselectrical conductivity, which increases directionally with theconcentration of electrolytes in the surrounding medium (e.g., saliva).In some embodiments, this “non-use” environment may even include rinsingor submersing the portion of the instrument that is normally placed inthe mouth (e.g., the head 905 of the toothbrush) in water (e.g., forpre-wetting or rinsing purposes), since the electrical conductivity ofsaliva is higher than that of water. This difference can thus beutilized to allow the instrument to “detect” when it is being used andthereby operate in an automatic mode.

Additionally, the combination of water, saliva, and dentifrice (e.g.,toothpaste or other ingredient that is generated in the mouth during useof the instrument) often affords even a significantly higher electricalconductivity than saliva alone. This is due to the generation of ions,often in large concentrations, from typical oral care products,including tooth fluoridating, whitening, and/or remineralizationproducts which contain or form aqueous cations, such as sodium (Na⁺),potassium (K⁺), calcium (Ca⁺²), magnesium (Mg⁺²), iron (Fe⁺³), etc. andanions, such as phosphate (PO₄ ⁻³), diphosphate (P₂O₇ ⁻⁴), carbonate(CO₃ ⁻²), fluoride (F⁻), chloride (Cl⁻), etc.

In view of the above, the increase in electrical conductivitysurrounding a portion of the toothbrush, e.g., head 905 or head 905 andneck 904, when placed in the mouth, can be used to complete anelectrical circuit, together with an electrical power or voltage sourcesuch as an external electrical outlet or an internal battery to activateLED driver 911, causing LED 960 to turn on.

In an “auto” position or setting, LED driver 911 is powered by the powersource only in the event that sufficient electrical conductivity (e.g.,a threshold level of conductivity, or sufficiently low resistance)exists between electrical conducting elements 907 in the neck 904. Therequired electrical conductivity, as needed for the “conditionalcompletion” of the electrical circuit to power motorized device it, maybe provided, for example, by an electrolyte solution containing ions(e.g., calcium, phosphate, fluoride, or peroxide ions) such as thatgenerated from a combination of saliva, water, and toothpaste existingin the oral environment during use. When the electrical conductivitybetween conducting elements 907 is no longer present, the electricalcircuit is incomplete, thereby deactivating LED driver 911 and LED 960.Thus, in an “auto” or automatic operating mode, LED driver 911 and LED960 will not be activated when the toothbrush is stored since air is themedium between electrical conducting elements 907. According to someembodiments, when the brush is being rinsed outside the mouth, the waterbetween electrical conducting elements 907 will not have sufficientelectrical conductivity to activate LED driver 911 and LED 960.

According to some embodiments, it may be desired to require that theelectrolyte solution (e.g., saliva or a water/saliva/toothpastemixture), to which the toothbrush is exposed during use, have athreshold (or minimum) level of conductivity before LED driver 911 isactivated. This threshold level of conductivity, for example, may bebased on a threshold (or minimum) current needed to activate LED driver911. This threshold conductivity, required to automatically turn on thetoothbrush, may be associated with the electrical conductivity of salivaalone or an electrolyte solution having a relatively higher conductivity(e.g., an aqueous solution of toothpaste) or lower (e.g., a mixture ofsaliva and water) conductivity. For example, the threshold conductivitymay be associated with a standard or model electrolyte solution designedto mimic the electrical conductivity of saliva having one or morespecified, additional concentrations of dissolved ions such as calciumphosphate, fluoride, peroxide, and other ions or mixtures of ions.

In this manner, the automatic functioning of the oral care instrumentcan be made more or less sensitive to the particular conditions orconditions associated with the environment in which the instrument isused (i.e., the “use” condition(s) required to activate the instrument).It is also possible that the sensitivity of the instrument can beadjusted by, set by, or tailored to, the user (e.g., to avoid eitheractivation of the instrument during “non-use” conditions ornon-activation during “use” conditions) and thereby ensure effectivefunctioning of the instrument in automatic mode.

In certain embodiments, the change in conductivity of the medium betweenelectrical conducting elements 907 is measured by a sensing device 938,such as a circuit board 938 or other suitable sensing device, connectedto electrical conducting elements 907 by electrical connections 940. Incertain embodiments, sensing device 938 may measure the drop inresistance between conducting elements 907. When the conductivity changereaches a preset value as detected by sensing device 938, switch 932 maybe activated so as to complete the electrical circuit to power LEDdriver 911. In such an embodiment, the electrical circuit need notinclude the electrolyte solution between conducting elements 907. Thatis, the electrolyte solution is used as a trigger to activate switch 932by way of sensing device 938, but does not actually form part of theelectrical circuit that powers LED driver 911.

In other embodiments, switch 932 could be activated based on thedifferential change in conductivity between conducting elements 907. Itis to be appreciated that the level of electrolyte in the medium willvary from person to person, and/or may vary based on the formula of theoral care solution used. In such embodiments, these variations will notaffect the current level delivered to the motor. Thus, for example, whenusing a sensitivity type toothpaste product having 5% KNO₃, thetoothbrush would not operate differently than when used with a standardtoothpaste product having a lower ionic strength.

According to other embodiments, when exposed to a solution with athreshold level of electrical conductivity, LED driver 911 and,therefore, the LED 960 itself may be set or adjusted (e.g., using atimer) to activate for a minimum duration. This ensures that thetoothbrush or other instrument will function for at least enough time toeffectively accomplish a given task (e.g., tooth cleaning and/orwhitening). This also promotes continuous operation, even if contactbetween the instrument and the electrolyte solution is temporarily lost,for example, when a toothbrush is temporarily removed from the mouthduring brushing. The minimum duration for activation of the LED (e.g.,two minutes) may be fixed or may otherwise be set or adjusted accordingto a user's preferences.

As discussed above, the ability of a dental instrument to “activate”(e.g., to turn on a motor) when exposed to the environment in which itis used (e.g., an electrolyte solution in the mouth) can obviate theneed for an “on/off” switch or button, creating a simplified operation.

Another embodiment of a motorized device activated when conductingelements 907 are exposed to an electrolyte solution is shown in FIG. 71.A reservoir 944 is provided in handle 901 for storing an active agent.Conducting elements 907 are used to activate a pump 946, which causes apredetermined quantity of the active agent to be delivered fromreservoir 944 through a channel 948 leading to a plurality of outlets950 located in head 905. An exemplary delivery system for an activeagent is described in U.S. application Ser. No. 11/457,086, the entiredisclosure of which is incorporated herein. Other examples of oral careinstruments that can activate an LED upon exposure of conductingelements 907 to an electrolyte solution will become readily apparent tothose skilled in the art, given the benefit of this disclosure.

In yet another embodiment, the sensor may be one or more accelerometerswithin a dental hygiene implement that detect the user's brushingmovement and compare it to previously stored brushing profiles todetermine if the brush is in use or not. In the embodiment shown in FIG.72, the dental hygiene implement is a toothbrush 100 with anaccelerometer 119 connected to a control circuit 110. If theaccelerometer 119 detects that the brush is in use, the control circuit110 will signal to the LED driver 111 to maintain the light source 117until the brushing time has expired. The brushing time is adjustable,and may be set by either the manufacturer or the user. If the brushingtime has expired, then the light source 117 will turn off and anindicator (not shown) will signal to the user that brushing has beencompleted. In one embodiment, the indicator is an additional LED lightlocated on the handle of the toothbrush. In another embodiment, theindicator is an audio signal relayed to the user.

One or more accelerometers may be installed in the toothbrush to measurethe x-, y- and z-axis of the toothbrush at any given moment while theuser is brushing his teeth. The control circuit may signal to the LEDdriver to turn on the light source when the accelerometers indicate thatthe toothbrush is in an orientation within a predetermined range. Inanother embodiment of the invention, there is a time delay between themoment the accelerometers indicate that the toothbrush is in a brushingorientation and the moment where the control circuit signals to the LEDdriver to turn on the light source.

In yet another embodiment, the user may pre-program his brushing patternto the control circuit such that the LED driver will only activate thelight source only when the control circuit recognizes the user'sbrushing pattern. In one embodiment, the control circuit signals to theLED driver to activate the light source for a predetermined amount oftime set by either the manufacturer or user. Alternatively, in anotherembodiment, the control circuit may continuously signal to the LEDdriver to keep the light source on until the accelerometer indicatesthat the user is no longer brushing.

In other embodiments of the invention, the sensor is a combination oftwo or more of these sensor types.

Embodiments may further include a mechanism for alerting a user that LED117 is about to be powered on. In some embodiments, toothbrush 100 mayinclude a light emitter to signal the status of LED 117. The lightemitter may be controlled in such a matter as to alert the user that thelight is about to come on to full power, through a gradual increase inpower from 5% of full power, up to 100% of full power, for a period ofbetween 0.5 seconds to 2 seconds before a complete and full power isachieved on the light emitting toothbrush. In one embodiment, the lightemitter may be an additional LED on toothbrush 100. In variousembodiments, the light emitter may operate by providing a short burst oflow frequency light pulses or flashes, using a rectangular, saw-tooth,pulsed, sinusoidal or other types of common periodic waveforms, in therange of 2-10 Hertz at partial or full power, for a period of betweenabout 0.5 seconds to about 5 seconds before full power is achieved onthe LED in the toothbrush 100. In combination or in the alternative,light emitter may also emit color-coded signals dependent on the amountof power supplied to LED 117. The color of the light emitter maygradually change from a first color to at least a second color as powerto the LED 117 gradually increases. Alternatively, the color of thelight emitter may change in discrete increments from a first color to atleast a second color as LED 117 gradually increases in power.

Other mechanisms may be used to alert a user of the power status of LED117. In one embodiment, a vibrator such as a motor may be incorporatedinto toothbrush 100. The vibrator may operate by providing a series ofpulsed vibration for a short duration of time, such as between about 0.5seconds to about 2 seconds, before LED 117 is fully powered. In anotherembodiment, the vibrator may provide a constant vibration withincreasing intensity as the power of LED 117 gradually increases. Thevibrator may be a motor used to drive the brush head of a motorizedtoothbrush. In yet another embodiment, toothbrush 100 may furtherinclude an auditory device for emitting a sound to alert a user of thepower status of LED 117. For example, the speaker may provide apulsating beep for a short duration to indicate that LED 117 is about toemit at full power.

One or more mechanisms may be included with toothbrush 100 to indicatethe upcoming power status of LED 117. These and other identifiers may beuseful as a safety feature to prevent a user from inadvertently lookingdirectly at LED 117 while it is fully powered.

It may be possible to inadvertently and momentarily break the interlocksafety circuit during normal brushing while the brush head is still inthe mouth. For example, when using the current loop embodiment of FIGS.1-8, such a momentary break may happen when the brush head is moved fromone side of the mouth to the other, breaking the biological circuitbetween the brush head and the brush handle. This break could cause thelight to momentarily shut-off while still in use, creating anunintentional flicker. To prevent this situation, the micro-controllercircuit can be programmed to introduce a shut-off delay such that thecircuit does not shut-off until the interlock circuit has been brokenfor more than a predefined period of time. In one embodiment, thepredefined period of time is between about 0.1 to about 0.5 seconds. Inanother embodiment, the break could cause the light to dim for a shortperiod, such as between about 0.1 to about 0.5 seconds before actuallyshutting off. If the interlock circuit is reengaged during this dimmedtime, the light goes back to full power without the need to alert theuser.

These embodiments and others may further include a fingerprint modulemounted on the handle to verify if the user is authorized. Inparticular, to keep children from playing with the device and defeatingthe safety measures that prevent the LED from coming on unless it is ina user's mouth, the fingerprint module may be included to only allow theLED to come on if a finger of a hand of an authorized adult is detected.The fingerprint reader may be a button or simply a surface. Variousfingerprint sensors are known and can be used in combination with theembodiments disclosed. The fingerprint reader preferably includes amemory for storage of fingerprint data of authorized users andsufficient processing capability to compare stored fingerprint data withnew data read as a user attempts to use the toothbrush. Alternatively,the toothbrush could include a data link as in the “internet of things”to compare the fingerprint data remotely and return a “match” or “nomatch” decision. In the embodiment shown in FIG. 73, the dental hygieneimplement is a toothbrush 100 having a LED 117 at the brush headconnected to a LED driver 111 located in the handle of the toothbrush.The control circuit 110 is connected to the LED driver 111 as well as abattery 109 and a fingerprint module 2126. The fingerprint module 2126may be initialized to recognize a user, with such information stored inthe control circuit 110. Subsequent uses of the toothbrush will requirethe user to verify his identity by placing his fingerprint on thefingerprint module 2126.

In one embodiment, if the user's identity is correct, then the user mayproceed to insert the brush head into his mouth and the LED will turn onin response to the installed sensor (not shown). If the user's identityis incorrect, then the LED will not turn on even if the installed sensordetects pressure, moisture, capacitance, etc. In another embodiment, thetoothbrush 100 may further include an on/off switch where thefingerprint module and LED remain completely inactive in the “off”setting. In yet another embodiment, the toothbrush 100 further includesan additional indicator to indicate whether the user is authorized. Thisindicator may be a visual light source that turns green when a user isauthorized to use the brush. A red light source may be activated toindicate that the user is not authorized to use the toothbrush. Othertypes of indicators may be used, such as an audio indicator.

FIG. 74 illustrates one example of a toothbrush having a fingerprintmodule for authorization. The fingerprint module may be presented as astart button for the user to depress and hold for a short duration 2200.The duration may be between about 1 to about 3 seconds. An indicator maybe provided to alert the user that the fingerprint has been read. In theexample provided, a green light flashes once the fingerprint is read2202. If an error occurs, the light may flash red and emit a sound 2204.Once the fingerprint is authorized, the light emitter may flash red andprovide a pulsing vibration and sound to alert the user that the LED isabout to become fully powered 2206. Simultaneously, the current loopdetector determines whether the toothbrush is being inserted into themouth (or a detector using any of the mechanisms as described in theembodiments above) 2210. If no current is detected after a preset timeinterval, then the toothbrush shuts off 2212. If a current is detected,then the LED and brush motor are activated 2216. A timer indicates whena sufficient duration of brushing has been reached by beeping anauditory signal to the user 2220. Once the user removes the brush fromthe mouth, the current loop is broken 2214. If the toothbrush remainsout of mouth for 30 seconds, the system turns off and the fingerprintreader will need to be used to reactivate system 2212.

FIG. 75 illustrates one embodiment of how the fingerprint module andstatus indicators are connected with other components of the toothbrushusing a circuit block diagram. The microcontroller 2300 is wired to thefollowing components: the fingerprint module 2302, a red LED 2304, agreen LED 2306, a beeper 2310, a current loop detector 2312, a LED/motordriver 2314, and a power supply 2322/2324. The LED/motor driver 2314 isresponsible for activating the UV LED 2316 and the brush head motor2320. LED/motor driver 2314 is also connected to the power supply2322/2324.

Of course, the fingerprint module and warning feature may be used withnon-motorized toothbrushes.

In another embodiment, the fingerprint module 2126 acts as the sensorfor toothbrush 100. The LED will turn on once an authorized user placeshis fingerprint over the module. In this embodiment, it is intended forthe user to place the fingerprint over the module only after the brushhead is inserted within the mouth.

Certain modifications and improvements will occur to those skilled inthe art upon reading the foregoing description. It should be understoodthat all such modifications and improvements have been omitted for thesake of conciseness and readability, but are properly within the scopeof the following claims.

What is claimed is:
 1. A toothbrush having a light source comprising: abrush including a battery, a source of light with a wavelength in therange of about 400 nm to about 500 nm, electronics coupled to thebattery and source of light to supply electricity from the battery tothe source at current and voltage that causes the source to emit light,the brush including a handle and a distal end; the distal end includingbristles mounted on the distal end and the source of light; at least aportion of the handle and at least a portion of the distal end beingequipped with a sensor to determine whenever the distal end is outsidethe environment of the mouth and permits activation of the source oflight only when the source of light is inside the mouth of the user, thesensor selected from the group consisting of: a capacitive sensor whichdetects current flowing through the body of a user when the brush heador bristles are in contact with the mouth and the handle is in contactwith the hand; a capacitive displacement sensor that senses change ofposition of any conductive target such as the human body; an inductivesensor that uses an inductance loop to measure the proximity ofconductors such as the human body; a passive thermal infrared thatdetects the warmth of the human mouth; a photoelectric sensor thatdetects reflected IR light emitted and absorbed by the sensor itself; alight sensor that is triggered by darkness inside the mouth; a lightsensor that detects the reflection of light from a second light sourceon the brush when the brush is activated; an ultrasonic and active sonarsensors that uses echo location to detect the confines of the mouth; amagnetic detector that detects the proximity of metals such as thehemoglobin present in blood; a pressure sensor under the brush head thatdetects movement and pressure of the brush head being pressed againstthe teeth; a pressure sensor in the neck that detects torque and tensionin the neck of the brush due to brushing action; a moisture sensor todetect a highly moist environment such as the mouth; and a combinationof two or more of these sensor types; a fingerprint sensor mounted onthe handle to verify if the user is authorized; and an alarm adapted towarn the user of the power status of the source of light.
 2. Thetoothbrush as claimed in claim 1 wherein the alarm is a light emitteradapted to alert the user that the source of light is about to operateat full power through a gradual increase in the power from about 5% offull power, up to 100% of full power, for a period of between 0.5seconds to about 5 seconds before the source of light reaches fullpower.
 3. The toothbrush as claimed in claim 2 wherein the light emitteroperates by providing a short burst of low frequency light pulses orflashes, using a rectangular, saw-tooth, pulsed, sinusoidal or othertypes of common periodic waveforms, in the range of about 2 Hertz toabout 10 Hertz at partial or full power, for a period of between about0.5 seconds to about 2 seconds before the source of light reaches fullpower.
 4. The toothbrush as claimed in claim 1 wherein the alarm is avibrator coupled with a light emitter to warn the user of the powerstatus of the source of light.
 5. The toothbrush as claimed in claim 4wherein the vibrator operates by providing a series of pulsed vibrationfor a period of between about 0.5 seconds to about 5 seconds before thesource of light reaches full power.
 6. The toothbrush as claimed inclaim 4 wherein the vibrator is a motor used to drive the bristles onthe distal end of the brush.
 7. The toothbrush as claimed in claim 1wherein the alarm is an auditory device emitting a sound to warn theuser of the power status of the source of light.
 8. The toothbrush asclaimed in claim 7 wherein the auditory device provides a pulsating beepfor a period of between about 0.5 seconds to about 5 seconds before thesource of light reaches full power.
 9. A toothbrush as claimed in claim1 wherein the sensor includes a pressure sensor selected from the groupconsisting of piezoelectric, capacitive, potentiometric, optical orelectromagnetic and combinations thereof.
 10. A toothbrush as claimed inclaim 1 wherein the sensor includes a moisture sensor that is acapacitive sensor, a chilled mirror dew point sensor, or combinationthereof.
 11. A toothbrush having a light source comprising: a brushincluding a battery, a source of light with a wavelength in the range ofabout 400 nm to about 500 nm, electronics coupled to the battery andsource of light to supply electricity from the battery to the source atcurrent and voltage that causes the source to emit light, the brushincluding a handle and a distal end; the distal end including bristlesmounted on the distal end and the source of light; a fingerprint sensormounted on the handle to verify if a user is authorized; an alarmmounted on the handle adapted to warn the user of the power status ofthe source of light; and at least a portion of the handle and at least aportion of the distal end each having an electrically conductiveexterior surface electrically connected to the electronics within thebrush, the conductive surfaces separated from one another by anon-conductive region of one of the handle or distal end to create anopen circuit, wherein the electronics has a control circuit to couplethe battery and the source of light and the open circuit, which can beclosed to sense when current from the battery is to be applied to thesource of light; whereby the user who uses the toothbrush to brush hisor her teeth by grasping the handle and inserting the bristles into hisor her mouth closes the open circuit to complete a signal loop that issensed by the electronics to turn on the source of light, and removal ofthe distal end from the mouth opens the circuit to break the signalloop, turning off the source of light.
 12. The toothbrush as claimed inclaim 11 wherein the alarm is a light emitter alerts the user that thesource of light is about to operate at full power through a gradualincrease in the power from about 5% of full power, up to 100% of fullpower, for a period of between about 0.5 seconds to about 5 secondsbefore the source of light reaches full power.
 13. The toothbrush asclaimed in claim 12 wherein the light emitter operates by providing ashort burst of low frequency light pulses or flashes, using arectangular, saw-tooth, pulsed, sinusoidal or other types of commonperiodic waveforms, in the range of about 2 Hertz to about 10 Hertz atpartial or full power, for a period of between about 0.5 seconds toabout 5 seconds before the source of light reaches full power.
 14. Thetoothbrush as claimed in claim 11 wherein the alarm is a vibratorcoupled with a light emitter to warn the user of the power status of thesource of light.
 15. The toothbrush as claimed in claim 14 wherein thevibrator operates by providing a series of pulsed vibration for a periodof between about 0.5 seconds to about 5 seconds before the source oflight reaches full power.
 16. The toothbrush as claimed in claim 14wherein the vibrator is a motor used to drive the bristles on the distalend of the brush.
 17. The toothbrush as claimed in claim 11 wherein thealarm is an auditory device emitting a sound to warn the user of thepower status of the source of light.
 18. A toothbrush having a lightsource comprising: a brush having a handle and a distal end, the brushincluding a battery, a source of light with a wavelength in the range of400 nm to 500 nm, a fingerprint sensor mounted on the handle; at leastone status indicator mounted on the handle adapted to warn the user ofthe power status of the source of light; electronics coupled to thebattery, the fingerprint sensor, the status indicator and the source oflight to supply electricity from the battery to the source of light atcurrent and voltage that causes the source to emit a light, thefingerprint sensor coupled to the electronics to indicate whether theuser is authorized, the electronics coupled to the status indicator tosupply electricity from the battery to the status indicator; a pluralityof bristles and the source of light mounted on the distal end; at leasta portion of the handle and at least a portion of the distal end eachbeing equipped with an electrical contact accessible on an exteriorsurface of the toothbrush, the electrical contacts completing a signalloop when both are in contact with a conductor; wherein the electricalcontacts act as sensors to determine whenever the distal end is outsidethe environment of the mouth and permits activation of the source oflight only when the source of light is inside the mouth of the user anda signal loop is completed through the electrical contacts.
 19. Thetoothbrush as claimed in claim 18 wherein the status indicator isselected from the group consisting of: a light emitter, a vibrationalmotor, and an auditory device.
 20. The toothbrush as claimed in claim 19wherein the status indicator operates by providing a series of pulsedfeedback for a period of between about 0.5 seconds to about 5 secondsbefore the source of light reaches full power.
 21. A toothbrush having alight source comprising: a brush including a battery, a source of lightwith a wavelength in the range of about 400 nm to about 500 nm,electronics coupled to the battery and source of light to supplyelectricity from the battery to the source at current and voltage thatcauses the source to emit light, the brush including a handle and adistal end; the distal end including bristles mounted on the distal endand the source of light; and at least a portion of the handle and atleast a portion of the distal end each having an electrically conductiveexterior surface electrically connected to the electronics within thebrush, the conductive surfaces separated from one another by anon-conductive region of one of the handle or distal end to create anopen circuit, wherein the electronics has a control circuit to couplethe battery and the source of light and the open circuit, which can beclosed to sense when current from the battery is to be applied to thesource of light, the control circuit continuing to supply power to thesource of light if the closed circuit becomes open for a duration ofbetween about 0.1 seconds to about 0.5 seconds; whereby the user whouses the toothbrush to brush his or her teeth by grasping the handle andinserting the bristles into his or her mouth closes the open circuit tocomplete a signal loop that is sensed by the electronics to turn on thesource of light, and removal of the distal end from the mouth opens thecircuit to break the signal loop, turning off the source of light afterthe duration of between about 0.1 seconds to about 0.5 seconds.
 22. Thetoothbrush as claimed in claim 21 wherein the control circuit suppliespower to the source of light at less than 100% for the duration ofbetween about 0.1 seconds to about 0.5 seconds when the closed circuitbecomes open.